The Collaborative International Dictionary of English v.0.48:

Nervous \Nerv"ous\ (n[~e]rv"[u^]s), a. [L. nervosus sinewy,
   vigorous: cf. F. nerveux. See Nerve.]
   1. Possessing nerve; sinewy; strong; vigorous. "Nervous
      arms." --Pope.
      [1913 Webster]

   2. Possessing or manifesting vigor of mind; characterized by
      strength in sentiment or style; forcible; spirited; as, a
      nervous writer.
      [1913 Webster]

   3. Of or pertaining to the nerves; seated in the nerves; as,
      nervous excitement; a nervous fever.
      [1913 Webster]

   4. Having the nerves weak, diseased, or easily excited;
      subject to, or suffering from, undue excitement of the
      nerves; easily agitated or annoyed.
      [1913 Webster]

            Poor, weak, nervous creatures.        --Cheyne.
      [1913 Webster]

   5. Sensitive; excitable; timid.
      [1913 Webster]

   6. Apprehensive; as, a child nervous about his mother's
      reaction to his bad report card.
      [PJC]

            Our aristocratic class does not firmly protest
            against the unfair treatment of Irish Catholics,
            because it is nervous about the land. --M. Arnold.
      [1913 Webster]

   Nervous fever (Med.), a low form of fever characterized by
      great disturbance of the nervous system, as evinced by
      delirium, or stupor, disordered sensibility, etc.

   Nervous system (Anat.), the specialized coordinating
      apparatus which endows animals with sensation and
      volition. In vertebrates it is often divided into three
      systems: the central, brain and spinal cord; the
      peripheral, cranial and spinal nerves; and the
      sympathetic. See Brain, Nerve, Spinal cord, under
      Spinal, and Sympathetic system, under Sympathetic,
      and Illust. in Appendix.

   Nervous temperament, a condition of body characterized by a
      general predominance of mental manifestations. --Mayne.
      [1913 Webster]

WordNet (r) 3.0 (2006):

nervous
    adj 1: easily agitated; "a nervous addict"; "a nervous
           thoroughbred"
    2: causing or fraught with or showing anxiety; "spent an anxious
       night waiting for the test results"; "cast anxious glances
       behind her"; "those nervous moments before takeoff"; "an
       unquiet mind" [syn: anxious, nervous, queasy, uneasy,
       unquiet]
    3: of or relating to the nervous system; "nervous disease";
       "neural disorder" [syn: nervous, neural]
    4: excited in anticipation [syn: aflutter, nervous]
    5: unpredictably excitable (especially of horses) [syn:
       skittish, flighty, spooky, nervous]

Moby Thesaurus II by Grady Ward, 1.0:

168 Moby Thesaurus words for "nervous":
   acid, agitable, agitated, all nerves, all-overish, allergic,
   anaphylactic, anxious, anxioused up, apprehensive, bashful, biting,
   bothered, concerned, corrosive, cowardly, critical, cutting,
   delicate, difficult, diffident, discomposed, disquieted,
   distressed, disturbed, driving, edgy, effective, emotional,
   emotionally unstable, empathetic, empathic, eruptive, excitable,
   excited, explosive, fearful, fearing, fearsome, feverish, fidgety,
   flurried, flustered, forceful, forcible, foreboding, fretful,
   frightened, goosey, goosy, gutsy, high-mettled, high-spirited,
   high-strung, highly emotional, hyperesthetic, hyperpathic,
   hypersensitive, imperative, impressive, in a dither, in a pucker,
   in a stew, in a sweat, in a tizzy, in fear, incisive, inflammable,
   irascible, irritable, itchy, jittery, jumpy, mettlesome, misgiving,
   mordant, mousy, nerval, nerves on edge, nervy, neural,
   neurological, on edge, on tenterhooks, overanxious,
   overapprehensive, overrefined, oversensible, oversensitive,
   overstrung, overtender, panicky, passible, penetrating,
   perturbable, perturbed, piercing, poignant, powerful, prickly,
   punchy, querulous, rabbity, refined, responsive, restless, ruffled,
   scared, scary, sensational, sensitive, shaken, shaken up, shaky,
   shivery, shrinking, shy, sinewed, sinewy, skittery, skittish,
   slashing, snappish, solicitous, spooky, startlish, stirred up,
   strained, striking, strong, strung out, supersensitive,
   suspenseful, sympathetic, tactful, telling, tender, tense, tetchy,
   thin-skinned, ticklish, timid, timorous, touchy, trembling,
   tremulous, trenchant, trepidant, trigger-happy, troubled,
   troublous, turbulent, twittery, uneasy, unpeaceful, unquiet,
   unrestful, upset, uptight, vigorous, vital, volatile, volcanic,
   waspish, worked up, worried, wrought up, zealous