What is "entasia"

Entasia \En*ta"si*a\, n. [NL., fr. Gr. ?. See Entasis.] (Med.) Tonic spasm; -- applied generically to denote any disease characterized by tonic spasms, as tetanus, trismus, etc. [1913 Webster] ||

n. (context medicine English) tonic spasm; any disease characterized by tonic spasms, such as tetanus or trismus