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déjà vu

A feeling of having already experienced the present situation, often associated with recognizing something familiar but not being able to pinpoint its source.

Examples:

Walking into the café, I felt a sense of déjà vu, recognizing a face but unable to recall where I knew them from.
The moment I saw her, déjà vu hit me like a wave, yet she remained a mystery.

familiarity paradox

The phenomenon where something feels familiar, yet the specific context or source of familiarity cannot be identified.

Examples:

I was caught in a familiarity paradox when I met him at the party, feeling like I knew him but not sure how.
The familiarity paradox often occurs in crowded places where faces blend into memories you can't quite access.

cognitive slip

A moment of forgetfulness, particularly in recalling where one has seen someone or something before.

Examples:

During the meeting, I had a cognitive slip when I recognized someone from a past conference but couldn’t remember their name.
Her cognitive slip left her frustrated; she stared at him, sure he was familiar, yet her mind was blank.

tip-of-the-tongue phenomenon

An inability to retrieve a specific piece of information, such as a name, although the information feels just within reach.

Examples:

I experienced the tip-of-the-tongue phenomenon when I recognized the actor, but his name eluded me.
That frustrating tip-of-the-tongue phenomenon happened again when I saw an old friend at the reunion.