What is the word for not being able to remember a word?

The most common word for not being able to remember a word is "tip of the tongue".

This phrase describes the frustrating experience of knowing you know a word, but being unable to recall it at that moment.

Other less common terms include:

* "Word block"

* "Lexical retrieval failure" (a more technical term)

* "Anomia" (a medical term for a more serious condition where there's a persistent difficulty finding words)