The quality of being able to start many projects without ever fully completing them. This can apply to one or more people, and is often times habitual.
"Dude, when are they gunna fix the hot tub at your apartment?"
"Who knows, the halfasseditude at that place is rediculous.
A passenger who is constantly on your ass about your driving skills. He/she constantly cautions you to keep a safe distance from the car in front of you, checks that you're obeying the speed limit, and is always quick to point out your navigational errors.
Guy riding shotgun: "Could you slow down a little? We're dangerously close to exceeding the speed limit by 5 mph."
Driver: "Quit being such a harassenger."
A master harasser is usually a faggot douche bag who has nothing better to do but annoy friends or foes because s/he is a failure who needs to compensate for his retarded mind set.