The Collaborative International Dictionary of English v.0.48:

Harass \Har"ass\ (h[a^]r"as or h[.a]*r[a^]s"), v. t. [imp. & p.
   p. Harassed (h[a^]r"ast or h[.a]*r[a^]st"); p. pr. & vb. n.
   Harassing.] [F. harasser; cf. OF. harace a basket made of
   cords, harace, harasse,a very heavy and large shield; or
   harer to set (a dog) on.]
   To fatigue; to tire with repeated and exhausting efforts;
   esp., to weary by importunity, teasing, or fretting; to cause
   to endure excessive burdens or anxieties; -- sometimes
   followed by out.
   [1913 Webster]

         [Troops] harassed with a long and wearisome march.
                                                  --Bacon.
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         Nature oppressed and harass'd out with care. --Addison.
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         Vext with lawyers and harass'd with debt. --Tennyson.

   Syn: To weary; jade; tire; perplex; distress; tease; worry;
        disquiet; chafe; gall; annoy; irritate; plague; vex;
        molest; trouble; disturb; torment.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Harass \Har"ass\, n.
   1. Devastation; waste. [Obs.] --Milton.
      [1913 Webster]

   2. Worry; harassment. [R.] --Byron.
      [1913 Webster]

WordNet (r) 3.0 (2006):

harass
    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]
    2: exhaust by attacking repeatedly; "harass the enemy"