Able to say something back with every single word right — nothing forgotten, nothing changed, nothing added. It is used for things that were learned by heart and then performed: an actor with their lines, a student with a poem, a singer with a song, someone giving a speech without notes. The praise inside the word is very specific, and that is the interesting part. It says the memory was exact; it says nothing at all about whether the performance was good. An actor can be word-perfect and still be wooden and boring — English speakers know this, and sometimes use the word with a small sting, exactly to say "the words were right, the feeling was not". So listen to the tone. It usually comes after a verb like "be" or "go": "she was word-perfect", "he went through it word-perfect". It is a little formal and a little British; Americans more often say "knew it perfectly" or "nailed every line". Note also that word-perfect is about the words themselves, so it fits a text someone must reproduce — not a skill like driving or cooking, where there are no words to get right.