Source : Webster's Revised Unabridged Dictionary (1913)

Lockjaw \Lock"jaw`\, n. (Med.)
   A contraction of the muscles of the jaw by which its motion
   is suspended; a variety of tetanus.

Source : WordNet®

lockjaw
     n : an acute and serious infection of the central nervous system
         caused by bacterial infection of open wounds; spasms of
         the jaw and laryngeal muscles may occur during the late
         stages [syn: {tetanus}]