The Collaborative International Dictionary of English v.0.48:

Harm \Harm\ (h[aum]rm), n. [OE. harm, hearm, AS. hearm; akin to
   OS. harm, G. harm grief, Icel. harmr, Dan. harme, Sw. harm;
   cf. OSlav. & Russ. sram' shame, Skr. [,c]rama toil, fatigue.]
   1. Injury; hurt; damage; detriment; misfortune.
      [1913 Webster]

   2. That which causes injury, damage, or loss.
      [1913 Webster]

            We, ignorant of ourselves,
            Beg often our own harms.              --Shak.

   Syn: Mischief; evil; loss; injury. See Mischief.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Harm \Harm\, v. t. [imp. & p. p. Harmed (h[aum]rmd); p. pr. &
   vb. n. Harming.] [OE. harmen, AS. hearmian. See Harm, n.]
   To hurt; to injure; to damage; to wrong.
   [1913 Webster]

         Though yet he never harmed me.           --Shak.
   [1913 Webster]

         No ground of enmity between us known
         Why he should mean me ill or seek to harm. --Milton.
   [1913 Webster]

WordNet (r) 3.0 (2006):

harm
    n 1: any physical damage to the body caused by violence or
         accident or fracture etc. [syn: injury, hurt, harm,
         trauma]
    2: the occurrence of a change for the worse [syn: damage,
       harm, impairment]
    3: the act of damaging something or someone [syn: damage,
       harm, hurt, scathe]
    v 1: cause or do harm to; "These pills won't harm your system"

Moby Thesaurus II by Grady Ward, 1.0:

166 Moby Thesaurus words for "harm":
   abomination, abuse, afflict, affliction, aggravate, aggrieve,
   atrocity, bad, badness, bane, banefulness, bankruptcy, befoul,
   befoulment, bewitch, blemish, blight, bother, breakage, breakdown,
   bugbear, burden, calamity, collapse, condemn, corrupt, corruption,
   crack-up, crippling, crucify, crushing burden, crying evil, curse,
   damage, death, defile, defilement, deleteriousness, deprave,
   despoil, despoliation, destroy, destruction, deteriorate,
   detriment, dilapidate, dilapidation, disablement, disaccommodate,
   disadvantage, discommode, disease, disoblige, disrepair, disserve,
   distress, do a mischief, do evil, do ill, do violence to, do wrong,
   do wrong by, doom, drawback, embitter, encroachment, endamage,
   envenom, evil, exacerbate, get into trouble, grievance, handicap,
   harass, havoc, hex, hobbling, hurt, hurting, ill, impair,
   impairment, impose upon, incapacitation, incommode, inconvenience,
   infect, infection, infliction, infringement, iniquity, injure,
   injury, inroad, irritate, jinx, liability, loss, loss of ground,
   maiming, make worse, maltreat, mar, mayhem, menace, mischance,
   mischief, misfortune, mistreat, misuse, molest, mutilation,
   nemesis, noxiousness, open wound, outrage, perniciousness,
   persecute, pest, pestilence, plague, play havoc with,
   play hob with, poison, pollute, pollution, prejudice, put back,
   put out, put to inconvenience, put to trouble, ruination,
   ruinousness, rum, running sore, sabotage, savage, scathe, scourge,
   sickening, spoil, spoiling, step backward, taint, tarnish,
   the worst, thorn, threaten, torment, torture, toxin, trouble,
   venom, vexation, violate, visitation, vitiate, weaken, weakening,
   wickedness, woe, worsen, wound, wreak havoc on, wrong,
   wrongdoing