Definition of "ha"

ha¹

/hɑː/

verb
1. (archaic) Alternative form of a (“have”)

ha²

/hɑː/

interjection
1. A representation of laughter.
2. An exclamation of triumph or discovery.
3. (archaic) An exclamation of grief.
4. (dated) A sound of hesitation: er, um.

ha³

/hɑː/

interjection
1. Said when making a vigorous attack.
  Quotations
  "That's well. Well," cried he, now for my turn. Ha! a hit! a hit!"
  1844 September, E.M. Walley, “Eighteen Months in Russia”, in The Covenant: A Monthly Magazine Devoted to the Cause of Odd-fellowship, volume 3, number 9, page 395
  I hit a cross-court forehand. “Ha ha haa. Great! Say, usin' cross-courts and angles like that is how O'Bramowitts beat Riggs."
  1988, Albemarle - Issues 3-7, page 49
  Mona: Hee! Ha! Ho! Ha! The brain buffet is closed, buddy! Take that! And this!
  1999, Mona the Vampire, "Attack of the Living Scarecrow" (season 1, episode 1a)
  Ha! Take that, you ugly, stupid devil, you.
  2008, Sheryl Foulk Rogers-Ramirez, Look What God Did for Our Marriage, page 37
  'I'm armed, you lot. And if you think you can take me alive . . Ha! Take that! And that! And that!'
  2009, Elizabeth George, In Pursuit of the Proper Sinner