The Collaborative International Dictionary of English v.0.48:

Amoeba \A*moe"ba\, Amoeba \A*m[oe]"ba\, n.; pl. L.
   Am[oe]b[ae]; E. Am[oe]bas. [NL., fr. Gr. ? change.]
   (Zool.)
   A rhizopod common in fresh water, capable of undergoing many
   changes of form at will. Same as ameba. See Rhizopoda.
   [1913 Webster]