noun

1. an acute infectious disease, often fatal, caused by the specific toxin of a bacillus (Clostridium tetani) which usually enters the body through wounds: it is characterized by spasmodic contractions and rigidity of some or all of the voluntary muscles, esp. of the jaw, face, and neck; lockjaw
2. Physiol. the state of continuous contraction of a muscle, esp. when caused experimentally by a series of rapidly repeated stimuli

Etymology: L < Gr tetanos, spasm (of muscles), lit., stretched < base of teinein: see thin