We found 20 dictionaries that define the word by heart:

General (17 matching dictionaries)

1. by heart: Merriam-Webster
2. by heart: Oxford Learner's Dictionaries
3. by heart: Collins English Dictionary
4. by heart: Vocabulary.com
5. by heart: Wordnik
6. (off) by heart: Cambridge Advanced Learner's Dictionary
7. by heart: Wiktionary
8. By heart, by heart: Dictionary.com
9. By Heart (Brenda K. Starr album), By Heart (Conway Twitty album), By Heart (Matt Finish album): Wikipedia, the Free Encyclopedia
10. by heart: Rhymezone
11. by heart: FreeDictionary.org
12. by heart: Mnemonic Dictionary
13. by heart: TheFreeDictionary.com
14. by heart: Wikimedia Commons US English Pronunciations
15. by heart: Longman Dictionary of Contemporary English

Medicine (1 matching dictionary)

16. by heart: Merriam-Webster Medical Dictionary

Miscellaneous (1 matching dictionary)

17. by heart: Idioms

Slang (1 matching dictionary)

18. by heart: Urban Dictionary

Definitions from WordNet (by heart) ▸ adverb:  by committing to memory ("She knew the poem by heart") Opposite: unfamiliar, unknown, unmemorized Phrases: to get by heart, to learn by heart, learn by heart, know by heart, Playing by Heart, more... ▸ Words similar to by heart ▸ Usage examples for by heart ▸ Idioms related to by heart ▸ Wikipedia articles (New!) ▸ Words that often appear near by heart ▸ Rhymes of by heart ▸ Invented words related to by heart