The Collaborative International Dictionary of English v.0.48:
Cardiidae \Cardiidae\ n. a natural family of somewhat heart-shaped sand-burrowing bivalve mollusks. Syn: family Cardiidae. [WordNet 1.5]WordNet (r) 3.0 (2006):
Cardiidae n 1: somewhat heart-shaped sand-burrowing bivalve mollusks [syn: Cardiidae, family Cardiidae]