The Collaborative International Dictionary of English v.0.48:

hassle \hassle\ n.
   1. An inconvenience caused by difficulties encountered trying
      to accomplish a task; as, finding a parking place in
      midtown is always a hassle.

   Syn: fuss, trouble, bother.
        [WordNet 1.5]

   2. disorderly fighting; an angry dispute or disturbance.
      [WordNet sense 2]

   Syn: hassle, scuffle, tussle, rough-and-tumble.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

hassle \hassle\ v. i.
   1. to dispute or quarrel, often over petty disagreements.
      [PJC]

   2. To expend excessive time and energy trying to accomplish a
      task.
      [PJC]

The Collaborative International Dictionary of English v.0.48:

hassle \hassle\ v. t.
   to repeatedly annoy; as, He is known to hassle his staff when
   he is overworked.

   Syn: harass, harry, chivy, chivvy, chevy, chevvy, beset,
        plague, molest, provoke.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

hassle
    n 1: an angry disturbance; "he didn't want to make a fuss";
         "they had labor trouble"; "a spot of bother" [syn: fuss,
         trouble, bother, hassle]
    2: disorderly fighting [syn: hassle, scuffle, tussle,
       dogfight, rough-and-tumble]
    v 1: annoy continually or chronically; "He is known to harry his
         staff when he is overworked"; "This man harasses his female
         co-workers" [syn: harass, hassle, harry, chivy,
         chivvy, chevy, chevvy, beset, plague, molest,
         provoke]