Source : Webster's Revised Unabridged Dictionary (1913)

Succuba \Suc"cu*ba\, n.; pl. {Succub[ae]}. [NL., fr. L.
   succubare to lie under; sub under + cubare to lie down; cf.
   L. succuba, succubo, one who lies under another.]
   A female demon or fiend. See {Succubus}.

         Though seeming in shape a woman natural Was a fiend of
         the kind that succub[ae] some call.      --Mir. for
                                                  Mag.

Source : WordNet®

succuba
     n : a female demon believed to have sexual intercourse with
         sleeping men [syn: {succubus}]