We found 44 dictionaries that define the word headache:

General (25 matching dictionaries)

1. headache: Merriam-Webster.com
2. headache: Oxford Learner's Dictionaries
3. headache: American Heritage Dictionary of the English Language
4. headache: Collins English Dictionary
5. headache: Vocabulary.com
6. Headache, headache: Wordnik
7. headache: Cambridge Advanced Learner's Dictionary
8. headache: Wiktionary
9. headache: Webster's New World College Dictionary, 4th Ed.
10. headache: The Wordsmyth English Dictionary-Thesaurus
11. headache: Infoplease Dictionary
12. headache: Dictionary.com
13. headache: Online Etymology Dictionary
14. headache: Cambridge Essential American English Dictionary
15. Headache (EP), Headache (Grimm), Headache (board game), Headache (disambiguation), Headache (game), Headache (journal), Headache (song), Headache: Wikipedia, the Free Encyclopedia
16. Headache: Online Plain Text English Dictionary
17. headache: Webster's Revised Unabridged, 1913 Edition
18. headache: Rhymezone
19. headache: AllWords.com Multi-Lingual Dictionary
20. headache: Free Dictionary
21. headache: Mnemonic Dictionary
22. headache: Dictionary/thesaurus
23. headache: Wikimedia Commons US English Pronunciations

Art (1 matching dictionary)

24. Natural Magick (No longer online)

Computing (1 matching dictionary)

25. headache: Encyclopedia

Medicine (13 matching dictionaries)

26. Dorland's Illustrated Medical Dictionary (No longer online)
27. Headache: MedTerms.com Medical Dictionary
28. Medical Dictionary (No longer online)
29. Headache: MedFriendly Glossary
30. online medical dictionary (No longer online)
31. Specific Diseases/Disorders (No longer online)
32. Headache: MEDLINE plus Illustrated Medical Encyclopedia
33. Disorder Index (No longer online)
34. headache: Medical dictionary
35. Rudy's List of Archaic Medical Terms (No longer online)
36. University of Maryland Glossary of Medical Terms (No longer online)
37. Headache: Drug Medical Dictionary
38. Hyperdictionary (No longer online)

Miscellaneous (2 matching dictionaries)

39. Brilliant Dream Dictionary (No longer online)
40. headache: Idioms

Slang (1 matching dictionary)

41. headache: Green’s Dictionary of Slang

Tech (1 matching dictionary)

42. Oil and Gas Well Drilling and Servicing eTool (No longer online)

(Note: See headaches as well.)

Definitions from Wiktionary ( ) ▸ noun:  (medicine) A pain or ache in the head. ▸ noun:  (figurative) A nuisance or unpleasant problem. Similar: vexation, worry, concern, cephalalgia, head ache, headake, head, headwark, hornache, headwound, more... Opposite: relief, comfort, ease, tranquility, peace Types: migraine, cluster, tension, sinus, more... Phrases: cluster headache, migraine headache, tension headache, splitting headache, vascular headache, more... Adjectives: severe, chronic, bad, sick, migraine, frontal, type, violent, splitting, slight, intense Colors:     gray,     black,     red,     dark blue,     purple, more... ▸ Word origin ▸ Words similar to headache ▸ Usage examples for headache ▸ Idioms related to headache ▸ Wikipedia articles (New!) ▸ Popular adjectives describing headache ▸ Words that often appear near headache ▸ Rhymes of headache ▸ Invented words related to headache