What word is on the tip of your tongue but you just can't think of it?

[HungLikeJesus]

I thought this was interesting:

The tip of the tongue (TOT or Tot) phenomenon is an instance of knowing something that cannot immediately be recalled. TOT is an experience with memory recollection involving difficulty retrieving a well-known word or familiar name. When experiencing TOT, people feel that the blocked word is on the verge of being recovered. Despite failure in finding the word, people have the feeling that the blocked word is figuratively "on the tip of the tongue." Inaccessibility and the sense of imminence are two key features of an operational definition of TOTs (A.S. Brown, 1991).

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Universality

Cognitive psychologist Bennett Schwartz examined fifty-one languages and found that forty-five of them include expressions using the word tongue to describe the TOT state. Some languages use multiple metaphors. In Korean, the metaphor "going round and round at the end of the tongue" is used, as well as "caught in the throat." French speakers use the "tongue" metaphor. In some languages, tongue is often replaced by lip, "I got it (the word) right on my lips", the concept remaining identical, and having an obvious relation to the tongue. The results of the language survey suggest that the use of the "tongue" metaphor is not idiomatic to English but instead a commonality of the TOT phenomenon. Research involving diaries kept of TOT experiences show that college students have approximately one or two TOTs per week, while elderly adults have about two to four TOTs per week (Schacter, 2001). TOTs occur most frequently for names of people, but for common words as well.