What does "ha" mean?

Ha: 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.