The Collaborative International Dictionary of English v.0.48:
Gaviiformes \Gaviiformes\ prop. n. An order of large aquatic birds, including loons and some extinct forms. Syn: order Gaviiformes. [WordNet 1.5]WordNet (r) 3.0 (2006):
Gaviiformes n 1: large aquatic birds: loons and some extinct forms [syn: Gaviiformes, order Gaviiformes]