zoosporangium

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A sporangium in which zoospores develop.

from The Century Dictionary.

• noun Any multicellular organ among the algæ or fungi giving rise to zoöspores.
• noun In botany, a sporangium or spore-case in which zoöspores or zoögametes are produced. See sporangium, and cuts under Puccinia and spermogonium.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Bot.) A spore, or conceptacle containing zoöspores.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun botany A sporangium, or conceptacle containing or producing zoospores.