I'm looking for a word to describe the state one is when forgetting something.
"Forgetful" seems not accurate, as this is more of a general character of not remembering things.
I'm talking about someone who realized he forgot something, and wants to refer to this state. e.g. John realized he forgot something, and wondered how long was he ______ (in the state of forgetting that something).
Does such a word exists?
I will pick-up where tchrist left in the comment section. Actually, this word was my primary choice because you were looking for a word expressing a forgetful state of the mind.
OP if you dig down into the etymology of the word "Oblivion", the primary definition of oblivion (late 14c) is "state or fact of forgetting" from Old French Oblivion (13c). https://www.etymonline.com/word/oblivion#etymonline_v_2432
Also, there is always lexical semantics in the play, when we use the word in the given context the word may mean little different, but not far from the root meaning. Even here, the word mean has different meanings in the given context: 1. to intend and 2. unkind or unpleasant.
The secondary meaning of the word oblivion in the contexts is: the state of being completely destroyed or the state of being unconscious. I will also recommend you to check the Cambridge Dictionary on the other definitions of the word: Oblivion. https://dictionary.cambridge.org/dictionary/english/oblivion
The Cambridge dictionary defines oblivion as:
Oblivion (noun) :No Memory
Meaning: the state of being completely forgotten:
Usage: These toys will be around for a year or two, then fade into oblivion.
John realized he forgot something, and wondered how long was he in the oblivion.
If you've completely forgotten something, and it's a systemic problem rather than just a momentary issue, then you are (or were) experiencing amnesia:
[Merriam-Webster]
1 : loss of memory due usually to brain injury, shock, fatigue, repression, or illness
2 : a gap in one's memory
3 : the selective overlooking or ignoring of events or acts that are not favorable or useful to one's purpose or position
If shock or fatigue are related, I suppose it could be appropriately used to describe momentary or episodic periods of forgetfulness.
But, generally, this is a term used only after a medical diagnosis, in a similar way to describing somebody as having anomic aphasia, Alzheimer's Disease or dementia. In which case, they could be said to be having "an episode."
For the routine inability to remember things, I don't think there's a more appropriate single word than just forget (or a variation) itself.
But there are several phrases that could be used to describe the situation:
A word that can be used to describe a state in which you do something but, later, cannot recall doing it is fugue:
[Merriam-Webster]
2 : a disturbed state of consciousness in which the one affected seems to perform acts in full awareness but upon recovery cannot recollect the acts performed
People can also talk about losing time or having blackouts.
More casual, and figurative, references to this type of thing include the word sleepwalking and the phrase on autopilot.
With limited context, I would suggest forgetfulness.
As in:
John realized he forgot something, and wondered again how long was this episode of his forgetfulness going to last.
tendency to forget
