ha Look up ha at Dictionary.com
c.1300, natural expression found in most European languages; in O.E., Gk., L., O.Fr. as ha ha. A ha-ha (1712), from Fr., was "an obstacle interrupting one's way sharply and disagreeably;" so called because it "surprizes ... and makes one cry Ah! Ah!" ["Le Blond's Gardening," 1712].