spasm

spasm involuntary rigid muscle contraction, often persistent and often accompanied by pain. It usually has some underlying physical cause such as disease, strain, or injury to the muscle or nearby tissues, impairment of circulation, or a disturbance of body chemistry. The spasm may be confined to one group of muscles or it may be severe and fairly generalized, as in convulsions . Painless localized spasms are called tics. These purposeless movements, usually of some part of the face, may begin as purposeful movement in response to some stimulus but eventually are carried out automatically, apparently without reason. They may disappear spontaneously after a time, or may require the elimination of some physical or psychic cause.

spasm Sustained involuntary muscle contraction. It may occur in response to pain, or as part of a generalized condition, such as spastic paralysis or tetanus.

spasm sudden or violent muscular contraction. XIV. — (O)F. spasme or L. spasmus, spasma — Gr. spasmǒs, spásma, f. spân draw, pull.
So spasmodic marked by spasms or twitches XVII; intermittent XIX. — modL. spasmōdicus, f. Gr. spasmṓdēs. spastic marked by spasmodic symptoms. XVIII. — L. spasticus — Gr. spastikṓs.