As`i·pho'ne·aA*si`pho*na'taAs`i*phon'i*da noun plural [ New Latin , from Greek 'a priv. + ... a tube.] (Zoology) A group of bivalve mollusks destitute of siphons, as the oyster; the asiphonate mollusks. Found on http://www.encyclo.co.uk/webster/A/129