The Collaborative International Dictionary of English v.0.48:

Oosporangium \O`o*spo*ran"gi*um\, n.; pl. L. Oosporangia, E.
   Oosporangiums. [NL., fr. Gr. w,'o`n an egg + ? vessel.]
   (Bot.)
   An oogonium; also, a case containing oval or rounded spores
   of some other kind than oospores.
   [1913 Webster]