a North American swallow (Petrochelidon pyrrhonota) that builds its gourdlike nest of mud, grass, etc. against a cliff or under the eaves of a building
See cliff swallow in American Heritage Dictionary 4
noun
A North American swallow (Petrochelidon pyrrhonota) that builds a bottle-shaped nest of mud, grass, and twigs on the face of a cliff or bluff or under the eaves of a roof.