The Collaborative International Dictionary of English v.0.48:

Essene \Es*sene"\, n.; pl. Essenes. [Gr. ?, lit., physicians,
   because they practiced medicine, fr. Chald [=a]say[=a] to
   heal, cf. Heb. as[=a].]
   One of a sect among the Jews in the time of our Savior,
   remarkable for their strictness and abstinence.
   [1913 Webster]