The Collaborative International Dictionary of English v.0.48:

Receptaculum \Rec`ep*tac"u*lum\
   (r[e^]s`[e^]p*t[a^]k"[-u]*l[u^]m), n.; pl. Receptacula
   (r[e^]s`[e^]p*t[a^]k"[-u]*l[.a]). [L.] (Anat.)
   A receptacle; as, the receptaculum of the chyle.
   [1913 Webster]