ha

American Heritage® Dictionary of the English Language, Fourth Edition

1. interj. Used to express surprise, wonder, triumph, puzzlement, or pique.
2. abbr. hectare.
3. abbr. Latin hoc anno (this year)
4. abbr. hour angle

Century Dictionary and Cyclopedia

1. An exclamation denoting surprise, wonder, joy, or other sudden emotion, as suspicion, and also interrogation. Repeated, ha! ha! it expresses either intensified surprise, etc., or laughter.
2. An involuntary sound marking hesitation in speech, uttered slowly and obscurely, and otherwise represented by er or ur.
3. n. An expression of wonder, surprise, or admiration.
4. n. An expression of hesitancy in speech.
5. To make the sound ha, expressing hesitation.
6. n. Same as ha-ha, haw-haw.
7. A dialectal variant of he.
8. n. A Scotch form of hall.
9. n. A contraction of have.
10. An abbreviation of hectare.

Wiktionary

1. n. hectare
2. v. archaic Alternate spelling of a4
3. interj. A representation of laughter.
4. interj. An exclamation of triumph or discovery.

GNU Webster's 1913

1. interj. An exclamation denoting surprise, joy, or grief. Both as uttered and as written, it expresses a great variety of emotions, determined by the tone or the context. When repeated, ha, ha, it is an expression of laughter, satisfaction, or triumph, sometimes of derisive laughter; or sometimes it is equivalent to “Well, it is so.”

WordNet 3.0

1. n. (astronomy) the angular distance of a celestial point measured westward along the celestial equator from the zenith crossing; the right ascension for an observer at a particular location and time of day