Ha \Ha\ (h[add]), interj. [AS.]

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.''

Ha-has, and inarticulate hootings of satirical rebuke. --Carlyle.

Source: Webster's Revised Unabridged Dictionary (1913)