know by heart
She knows the entire poem by heart.
She has memorized the poem perfectly.
to have memorized something perfectly without needing to read it
The actor knows his lines by heart.
The actor has memorized his script without relying on notes.
I know the multiplication table by heart.
I have memorized all the multiplication facts.
Often used for speeches, songs, scripts, or lists where recall is important.
Collocations
Related Phrases
Pro Tip
Memory Technique
To 'know by heart,' try the Feynman Technique: explain the concept aloud as if teaching someone else. This reveals gaps in your memory.
Gold Rule
Usage Context
Use 'know by heart' for skills or knowledge that require perfect recall, like scripts, songs, or mathematical tables. Avoid for abstract concepts that don't need verbatim memorization.
Word Origin
The phrase dates back to the 15th century, combining 'know' (Old English 'cnāwan') with 'heart' as the seat of memory or understanding in medieval thought.
Usage Notes
Common in both formal and informal contexts. Often used when emphasizing effortless recall, though rote memorization may imply lack of deep understanding.