'Ha-ha' definitions:

Definition of 'ha-ha'

(from WordNet)
noun
A loud laugh that sounds like a horse neighing [syn: hee- haw, horselaugh, ha-ha, haw-haw]
noun
A ditch with one side being a retaining wall; used to divide lands without defacing the landscape [syn: sunk fence, ha- ha, haw-haw]

Definition of 'Ha-ha'

From: GCIDE
  • Ha-ha \Ha-ha"\ (h[aum]*h[aum]"), n. [See Haw-haw.] A sunk fence; a fence, wall, or ditch, not visible till one is close upon it. [Written also haw-haw.] [1913 Webster]