In English, I think it is fairly obvious when some words have a prefix. For example,

recall, return, remove, superconductor, etc.

You can actually separate the prefix from the root word and have a root word with a different meaning.

But other words aren’t so clear like,

repeat, redundant, etc.

Obviously the root words in these situations are in Latin or a different language, or maybe there isn’t a prefix and the word is one unit. Is there an easy way to determine if something is a prefix or not? For example, submarine and substance both start with sub- but I am inclined to think the sub- in substance is not a prefix because the meaning of sub- is under, but substance lacks that meaning.

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    What's your definition of a true prefix? English has various categories of prefix - there are productive prefixes, non-productive prefixes, prefixes in words taken from other languages (where if you know the language you may be able to form a new English word), prefixes which don't seem to change the meaning of words (con-), as well as compound words where the first part is a word in its own right.
    – Stuart F
    Commented Nov 9, 2022 at 10:02

1 Answer 1


Most dictionaries define a prefix as

a letter or group of letters added to the beginning of a word to make a new word. (Cambridge)

So if you follow that, you can identify a prefix by removing it and seeing if you are left with a word or rather a part of a word that has no meaning in English.

EDIT: Prompted by a certain sigh, I am adding a more accurate definition of prefix:

an affix attached to the beginning of a word, base, or phrase and serving to produce a derivative word or an inflectional form (M-W)

In his article Some Important Prefix Types, Paul Fanning follows the same line:

post- in postpone and posthumous is not a prefix because -pone and -humous are not possible words. (guinlist).

But if you dig in the etymology of each word, you will discover that although some words may not look like they have a prefix in English, they did have one in the language in which they were born and came into English with it. Not all dictionaries provide etymology, but Etymonline is helpful in this matter.

Thus re- in repeat was a prefix in Latin (same for redundant):

from from Old French repeter, from re- "again" + petere "to go to; attack; strive after; ask for, beseech" (from PIE root *pet- "to rush, to fly").

It is true that *-peat is not an English word before which re- was stuck, the process happened way before it became an English word. So you are not wrong in thinking that it's no use dissecting the word in re-peat. I personally prefer to know that the meaning of the Latin prefix re- is included in this word, because it helps me understand and assimilate it better. This is the same re- you find in remove and recall.

Substance is an interesting word. The word stance was so fused with the prefix sub- that it is hard to say it contains a prefix. However, you are left with stance after removing the prefix, and stance is an English word. Etymonline says it comes:

from sub "up to, under" + stare "to stand," from PIE root *sta- "to stand, make or be firm."

Substance came into English as a philosophical and theological term:

The Ancient Greek term ousia was translated in Latin as essentia or substantia, and hence in English as essence or substance. (Wikipedia)

Substantia was understood like something firm under your feet that helps you stand and not crumble into nothingness. This meaning was not preserved in English.

It is in the 14th century that the meaning of the word shifted to what we are more familiar with today:

Meaning "any kind of corporeal matter" is first attested mid-14c. Sense of "the matter of a study, discourse, etc." first recorded late 14c. (Etymonline)

I would argue that if you use substance in philosophical or theological contexts, you'd better be aware of the prefix sub-. If you use it with its wider meaning, then the prefix is less important and may be ignored. I would personally still consider it a prefix whose meaning is obscured in modern use, but was relevant in the past.

In his dictionary Ologies and Isms: Word Beginnings and Endings, British etymologist and writer Michael Quinion says:

Some examples where sub‑ became attached in Latin, and in which it has a figurative association in English, include subdue (ducere, to lead or draw); sublime (in which the second element may be related to limen, threshold); subscribe (scribere, to write); subjugate (jugum, yoke); submit (mittere, to send, put); and subsequent (sequi, to follow).

I would include substance in this category.

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    "a letter or group of letters" ... sigh Commented Nov 9, 2022 at 16:20
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    @AzorAhai-him- Your comment made me smile and realise that indeed, Cambridge's dictionary is simplistic. I hope my edit will replace the sigh with a smile :)
    – fev
    Commented Nov 9, 2022 at 16:32
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    Just flashbacks to many a dinner conversation trying to explain to people that words != letters Commented Nov 9, 2022 at 16:49
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    I found this answer to have the appropriate amount of detail. It was adequately petative and sufficiently dundat.
    – R.M.
    Commented Nov 9, 2022 at 19:07
  • 1
    @R.M. You mean, petitive and dundant?
    – fev
    Commented Nov 9, 2022 at 19:20

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