The Collaborative International Dictionary of English v.0.48:

Enema \En"e*ma\, n.; pl. L. Enemata. [L. enema, Gr. ?, fr. ?
   to send in; ? in + ? to send.] (Med.)
   An injection, or clyster, thrown into the rectum as a
   medicine, or to impart nourishment. --Hoblyn.
   [1913 Webster]