The Collaborative International Dictionary of English v.0.48:
Lemnaceae \Lemnaceae\ n. A natural family of small free-floating thalloid plants. Syn: family Lemnaceae, duckweed family. [WordNet 1.5]WordNet (r) 3.0 (2006):
Lemnaceae n 1: family of small free-floating thalloid plants [syn: Lemnaceae, family Lemnaceae, duckweed family]