When I look up unforgettable in a thesaurus, I get words like enduring, remarkable, or exceptional. These all are positive; I just cannot forget such a wondrous thing!

I, however, want a word that means unforgettable because it was so horrible. As in, I cannot forget such a horrible thing that has happened.

Any suggestions?

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    A "haunting memory" or an "unshakable memory" might work.
    – Sven Yargs
    Commented Nov 17, 2014 at 22:54
  • 3
    +1 for haunting. That should just be the answer.
    – Carl Smith
    Commented Nov 17, 2014 at 23:05
  • 3
    I like haunting, but I think there are many kinds of memories that may be negative but not necessarily haunting. For example, as a purposeless 20-year-old I had to pick blueberries for several weeks to earn enough money to buy a bus ticket home. It was horrible. I'd like to forget about it. But I would never call it haunting. I feel that haunting is most appropriate for things that we witness, or things we experience but without consciously choosing them.
    – Rusty Tuba
    Commented Nov 18, 2014 at 0:23
  • 5
    Note that haunting can also be used of things that are quite positive, though usually only if their effect has become negative in the situation. So you can have haunting memories of your happy childhood (because you miss your family who have all died now) or of your college sweetheart (with whom you were very happy, but who has since left you and married a plumber named Bob). Commented Nov 18, 2014 at 0:49
  • 4
    Seems no one has mentioned “scarring.” This seems to be exactly what you're looking for.
    – HalosGhost
    Commented Nov 19, 2014 at 0:11

20 Answers 20


For some purposes, I like:

indelible: making marks that cannot be removed

It makes me thinks of spills, stains, bad tattoos, burns... things that you want to delete, but can't.

Though I think @Sven-Yargs hit it on the head with haunting.

  • 1
    +1 indelible (memories). I think it is the most common adjective that can be used for unforgettable bad memories and events.
    – ermanen
    Commented Nov 18, 2014 at 3:37
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    "Indelible" certainly collocates nicely with "memory," but it is by no means used exclusively for bad memories or experiences. Google "indelible" and look at the examples in your dictionary sources and you'll find a balance of positive and negative.
    – Rusty Tuba
    Commented Nov 18, 2014 at 12:13
  • 2
    +1 just for haunting. Indelible just means permanent.
    – Daniel
    Commented Nov 19, 2014 at 3:24
  • Indeed @RustyTuba, there are even pens which are marketed as using "indelible ink". If indelible had any negative connotation, it wouldn't be used to convince people to buy a product.
    – talrnu
    Commented Nov 19, 2014 at 20:18
  • @talrnu Have you ever heard of someone making the mistake of using a permanent marker on a whiteboard?
    – Barmar
    Commented Nov 24, 2014 at 19:38

traumatic may fit, even though the word means basically "causing mental or emotional problems, usually for a long time".

It was a traumatic experience for all of us.

Not all unforgettable events are traumatic but most traumatic events will be unforgettable.

  • Cf. my comment above at rhrgrt's post. Traumatic events usually are hard to forget for the reasons described there, so "traumatic" is closely related. But it encompasses all of the damage or injury done by an experience which goes beyond the mere inability to forget. Commented Nov 18, 2014 at 10:14

You would be able to get away with seared into my memory or similar variations as a phrase to describe such an event.

The train crash I saw that afternoon was seared into my memory.

The report on teen drug use seared itself into my memory.

I cannot think of any adjectives that would suit your purpose, however.

  • This is the best match. I really think "seared" captures it perfectly. However Steven Kath's indelible is just too perfect as an adjective with a definition that matches so well
    – BigBoy1337
    Commented Nov 18, 2014 at 7:49
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    I wanted to suggest something along that proposal ("burned in" or so). It's worth noting that it actually describes the conditioning of the nervous system and the brain happening when we go through traumatic experiences. It's well known that emotional events usually are remembered better. If the emotions are too strong they "overload" the nervous system and quite literally burn signal paths in which can easily be triggered later and lead to unvoluntary and hard to control reactions -- PTSD. So I like this metaphor because it almost isn't one. Commented Nov 18, 2014 at 10:08
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    Scaring, particularly for negative memories from early in life. Commented Nov 18, 2014 at 22:29

If you're looking for adjectives, as opposed to phrases, then I think there are three good candidates:

inextirpable: incapable of being destroyed

inexpungible: incapable of being obliterated

inerasable: incapable of being erased

Of course, the implication with these words is that we might, in fact, like to destroy, obliterate, or erase the things they describe. They would be good fits for describing a memory that you would rather not have but can't seem to rid yourself of.

  • 7
    These are not common words that would go with memories. Inextirpable memories? Inexpungible memories? I don't think anyone would use them. Inerasable, somewhat, can be used but still very uncommon to say "inerasable memories"
    – ermanen
    Commented Nov 18, 2014 at 2:43
  • 4
    The question didn't stipulate commonness as a key criterion
    – Rusty Tuba
    Commented Nov 18, 2014 at 2:44
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    It doesn't have to, it is common sense. The context is obvious so it would be nice to give answers that can be used in these situations. Also you said they are good fits for describing a memory but they are not.
    – ermanen
    Commented Nov 18, 2014 at 2:55
  • 3
    Common sense is not an argument. The context is not at all obvious. We know the general meaning of BigBoys search word, but not whether he's explaining something to a few chums at the local or writing a piece of literary fiction in which he's unafraid to challenge his reader. I was going for precision; words like " haunting" and "indelible" may be somewhat more familiar, but they are not as precise. To be honest, I'm a bit surprised by your comment because I've appreciated many of your word choice answers exactly because they are so precise and unafraid of obscurity!
    – Rusty Tuba
    Commented Nov 18, 2014 at 3:24
  • 1
    I just up-voted your answer. Because I liked your justification and the tone of your discussion, you might almost convince me to use these words also :)
    – ermanen
    Commented Nov 18, 2014 at 3:45

"What has been seen cannot be unseen". Slang.

For citations see: http://en.wiktionary.org/wiki/Citations:what_has_been_seen_cannot_be_unseen


At Dachau he was witness to real rather than abstract suffering; what has been seen cannot be unseen, nor can it be rationalized.

Brad Prager, "Suffering and Sympathy in Volker Schlöndorff's Der neunte Tag and Dennis Gansel's NaPolA", in Screening War: Perspectives on German Suffering (eds. Paul Cooke & Marc Silberman), Camden House (2010), ISBN 9781571134370, page 196

Also, although 'unforgettable' by itself has a positive connotation, 'unforgettably' doesn't necessarily. E.g. The incident was was unforgettably traumatic


I like an inescapable memory.

The escape implies a concerted effort to relieve oneself of the memory. I find it's less passive. Requires the 'memory' after unfortunately.

Edit: I realised this was very similar to Rusty Tuba's answer... but I've posted it now.


Memory already implies that the thing is being remembered and not forgotten, so I would prefer a word to describe the type of memory being referenced, while also conveying that it is a memory that is constantly being revisited. So things like

  • bedeviling memory
  • tormenting memory
  • the memory of it plagued me
  • accursed memory
  • fiendish memory
  • vexing / vexatious memory

and, my favorite, oppressive memory.


As an adjective, there is never-to-be-forgotten which usually implies that the experience or memory was unpleasant, unlike unforgettable which usually implies a pleasant memory.

Note: It is used as unhyphenated too.


Stupid, sometimes tragic, decisions by commanders also impacted the mind with never-to-be-forgotten, nightmarish memories.

[Never Without Heroes: Marine Third Reconnaissance Battalion in Vietnam by Lawrence C. Vetter, Jr. (2011)]

At length, the never-to-be-forgotten day of the terrible auction arrived, when the 'slaves, horses, and other catde' of Charles Ardinburgh, deceased, were to be put under the hammer, and again change masters.

[The Narrative of Sojourner Truth by Sojourner Truth (2008)]

There is etched (in/on sb's memory) that can used for unforgettable bad memories. It is mainly used in literature. Similarly there is engraved and stamped but they are more neutral.

if something is etched on your mind or memory, you can still remember it very clearly, sometimes when you would prefer to forget it



The plane crashed on landing as family and friends watched from the airport lounge while awaiting their loved one's arrival. Those horrible images were forever etched in his memory.

[Softened Moon's Glow: Collective Works (BW) by Don Di Tomasso, ‎Connie L. Valentine - (2013)]

The sudden demise of my younger brother was now permanently etched in my mind. The end of my brother's life created permanent pain into the deep divisions of my mind and heart.

[Survival of the Heart Tragedy of the Mind By Dwight N. Wood (2013)]

  • This would work, but note that it has a neutral rather than negative connotation.
    – Charles
    Commented Nov 18, 2014 at 2:17
  • @Charles: Which one? Etched is usually used in negative situations.
    – ermanen
    Commented Nov 18, 2014 at 2:28
  • Etched -- the other was added after my comment. I've certainly heard this used of good or even joyful memories.
    – Charles
    Commented Nov 18, 2014 at 2:32
  • @Charles: Yes, that is why I said "usually", not "always". Unforgettable is used for bad memories also.
    – ermanen
    Commented Nov 18, 2014 at 2:33
  • 2
    @Charles: Fair enough. Nice research. It will be etched in my memory :)
    – ermanen
    Commented Nov 18, 2014 at 3:49

How about infamous? A la "a day that will live in infamy!"

  • 1
    You beat me to it..."It means murderous, evil. All like you said. And it will save you money." Commented Nov 19, 2014 at 0:38
  • @2NinerRomeo Actually, user98109 beat both of you.
    – Mazura
    Commented Nov 20, 2014 at 4:55
  • An important lesson in English language and usage: youtube.com/watch?v=BFFXe3Rljro Commented Nov 20, 2014 at 5:29

In addition to the wonderful words suggested so far, also consider ineradicable:

not able to be eradicated; of root, too deep to remove

From en.wiktionary, eradicate means “(to pull up by the roots): root up, uproot” and “(to completely destroy): annihilate, exterminate, extirpate”. Thus, ineradicable means “not able to be destroyed”.

Note, the Wikisaurus page for destroy includes the verb devastate, which according to en.wiktionary has several senses that all connote major destruction. The word devastating can be used to mean confounding or overwhelming, “as with grief or shock” [www.collinsdictionary], and one might refer to a devastating memory, a devastating experience, an overwhelming experience, etc.


It sounds like a traumatising memory: not merely traumatic, but leaving a permanent mental scar.


A pest is something that will not let you forget it exists.

Edited to add haunting.

That memory will haunt me for the rest of my life.


I believe the word is infamous.

  • Fame is a collective knowledge, infamy something which will not vanish from the collective consciousness. The question is about personal experience. "I cannot forget", with no consideration of whether or not other people have forgotten.
    – itsbruce
    Commented Nov 18, 2014 at 13:43

I propose "unignorable" which implies persistence, and suggests undesirability: forgetting can be accidental, but ignoring is deliberate. It's admittedly a somewhat unwieldy word, but I believe it's close to meeting the questioner's need. I also like "indelible": that which we would like to delete but cannot.


Traumatic, horrific, catastrophic, terrifying, tragic...These are all off the top of my head.

I used: www.thesaurus.com to get these:
Haunting, grievous, heinous, scandelous, egregious, and infamous

Flagrant might also work. According to www.dictionary.com it means:
"1. shockingly noticeable or evident; obvious; glaring
2. notorious; scandalous:"

Check out: http://www.thesaurus.com/browse/flagrant

Then I typed in one of the previous words and got other choices.


I think Notorious would fit perfectly in many contexts.

notorious nə(ʊ)ˈtɔːrɪəs/Submit adjective famous or well known, typically for some bad quality or deed.

  • 2
    No, it would not. Notoriety lives in the minds of the many, while the question is specifically about one person's reaction: "I cannot forget..."
    – itsbruce
    Commented Nov 18, 2014 at 13:45

The word 'heinous' being synonymous with horrible or horrific is certainly 'reprehensible' to the memory of an innocent person who would witness the act.


How about the word “scarring”?

TFD gives:

v. scarred, scar·ring, scars v.tr.

  1. To mark with a scar.
  2. To leave lasting signs of damage on

With the exception of "exceptional", I would say those words can have a negative connotation even though they are typically used in a positive way.

"Enduring" is something that has a long lasting effect.

The training for military was so enduring that it will always be with me

"Remarkable" is something extremely out of the ordinary

I will always remember seeing that remarkable crash

Both of these are typically something that may very well be hard to forget

However, without more context, "horrendous" would be the first thing that comes to mind for me when thinking about something negative that is hard to forget.

Their actions towards those innocent people were so horrendous that I can't imagine someone really doing such a thing.

Checking this thesaurus link "appalling" could fit, as well.

While they aren't synonyms, the meaning they have certainly gives the feeling of something that wouldn't be easily forgettable.


{Something} I'd rather forget.

  • 1
    That's a phrase and really doesn't carry any meaning of "horrific".
    – itsbruce
    Commented Nov 18, 2014 at 13:34

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