nervous

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Of or relating to the nerves or nervous system.
• adjective Stemming from or affecting the nerves or nervous system.
• adjective Easily agitated or distressed; high-strung or jumpy.
• adjective Marked by or having a feeling of unease or apprehension.
• adjective Vigorous in style or feeling; spirited.
• adjective Archaic Strong; sinewy.

from The Century Dictionary.

• Full of nerves.
• Sinewy; strong; vigorous; well-strung.
• Possessing or manifesting vigor of mind; characterized by force or strength in sentiment or style: as, a nervous historian.
• Of or pertaining to the nerves; seated in or affecting some part of the nervous system: as, a nervous disease; a nervous impulse; a nervous action.
• Having the nerves affected; having weak ordiseased nerves; easily agitated or excited; weak; timid.
• In botany, same as nerved.
• Synonyms Forcible.
• Timorous, excitable, high-strung.

from the GNU version of the Collaborative International Dictionary of English.

• adjective Possessing nerve; sinewy; strong; vigorous.
• adjective Possessing or manifesting vigor of mind; characterized by strength in sentiment or style; forcible; spirited.
• adjective Of or pertaining to the nerves; seated in the nerves
• adjective Having the nerves weak, diseased, or easily excited; subject to, or suffering from, undue excitement of the nerves; easily agitated or annoyed.
• adjective Sensitive; excitable; timid.
• adjective Apprehensive.
• adjective (Med.) a low form of fever characterized by great disturbance of the nervous system, as evinced by delirium, or stupor, disordered sensibility, etc.
• adjective (Anat.) the specialized coördinating 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.
• adjective a condition of body characterized by a general predominance of mental manifestations.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective Easily agitated or alarmed; on edge or edgy.
• adjective Apprehensive, anxious, hesitant, worried.
• adjective Relating to or affecting the nerves.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• adjective easily agitated
• adjective excited in anticipation
• adjective of or relating to the nervous system
• adjective unpredictably excitable (especially of horses)
• adjective causing or fraught with or showing anxiety