What does "nervous" mean?

Additional senses

1. 2.Of or pertaining to the nerves; seated in the nerves; as, nervous excitement; a nervous fever.
2. 3.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.
3. 4.Sensitive; excitable; timid. Our aristocratic class does not firmly protest against the unfair treatment of Irish Catholics, because it is nervous about the land. M. Arnold. 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 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. -- Nervous temperament, a condition of body characterized by a general predominance of mental manifestations. Mayne.