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.
Impulse conduction - an impulse is simply the movement of action potentials along a nerve cell. Action potentials are localized (only affect a small area of nerve cell membrane). So, when one occurs, only a small area of membrane depolarizes (or 'reverses' potential).