"enclosure," Old English haga "enclosure, fortified enclosure; hedge," from Proto-Germanic *hag- (source also of Old Norse hagi, Old Saxon hago, German Hag "hedge;" Middle Dutch hage, Dutch haag, as in the city name The Hague), from PIE root *kagh- "to catch seize; wickerwork fence" (see hedge (n.), and compare hag). Meaning "fruit of the hawthorn bush" (Old English) is perhaps short for *hægberie.
"hesitate in speech," 1580s, imitative. Related: Hawed; hawing. The noun in this sense is from c. 1600. Haw-haw in reference to a style of affected upper class British enunciation is from 1841, imitative.