Source : Webster's Revised Unabridged Dictionary (1913)

Nervous \Nerv"ous\, a. [L. nervosus sinewy, vigorous: cf. F.
   nerveux. See {Nerve}.]
   1. possessing nerve; sinewy; strong; vigorous. ``Nervous
      arms.'' --Pope.

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

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

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

            Poor, weak, nervous creatures.        --Cheyne.

   5. Sensitive; excitable; timid.

Source : WordNet®

nervous
     adj 1: easily agitated; "quick nervous movements"
     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}, {uneasy}, {unquiet}]
     3: of or relating to the nervous system; "nervous disease";
        "neural disorder" [syn: {neural}]
     4: excited in anticipation [syn: {aflutter}]
     5: unpredictably excitable (especially of horses) [syn: {skittish},
         {spooky}]