A word is one or more sounds that in combination have a specific meaning assigned by a language. The symbolic meaning of words can be so powerful that people are willing to risk their lives for them or take the lives of others.
A nerve impulse is the relaying of a coded signal from a nerve cell to an effector (a muscle cell, a gland cell or another nerve cell) in response to a stimulus. It is the means by which a nerve cell communicates with another cell.
Medical Definition of Nerve Nerve: A bundle of fibers that uses electrical and chemical signals to transmit sensory and motor information from one body part to another. The fibrous portions of a nerve are covered by a sheath called myelin and/or a membrane called neurilemma. (Note that entries for specific nerves can be found under the names of the particular nerves. For example, the optic nerve is not under 'nerve, optic' but rather under 'optic nerve.')