A painful and involuntary muscular contraction WordNet 3.0 & Open English WordNet

A spasm is a sudden involuntary contraction of a muscle; a group of muscles; or a hollow organ, such as the bladder. Wikipedia

A cramp is a sudden, involuntary, painful skeletal muscle contraction or overshortening associated with electrical activity; while generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affected muscle. Wikipedia

Sudden, involuntary contraction of a muscle, a group of muscles or a hollow organ. Wikipedia Disambiguation

Sudden, involuntary muscle contraction, often temporarily painful and paralysing. Wikipedia Disambiguation

Involuntary contraction of a muscle, organ or orifice Wikidata

Pathological, often painful, involuntary muscle contraction Wikidata

A painful and involuntary muscular contraction. OmegaWiki

A painful contraction of a muscle which cannot be controlled. Wiktionary

Painful contraction of a muscle. Wiktionary (translation)

A sudden, involuntary contraction of a muscle, a group of muscles, or a hollow organ. Wiktionary