The Collaborative International Dictionary of English v.0.48:
Bird's nest \Bird's" nest`\, or Bird's-nest \Bird's-nest\, n.
1. The nest in which a bird lays eggs and hatches her young.
2. (Cookery) The nest of a small swallow (Collocalia
nidifica and several allied species), of China and the
neighboring countries, which is mixed with soups.
Note: The nests are found in caverns and fissures of cliffs
on rocky coasts, and are composed in part of alg[ae].
They are of the size of a goose egg, and in substance
resemble isinglass. See Illust. under Edible.
3. (Bot.) An orchideous plant with matted roots, of the genus
Neottia (Neottia nidus-avis).
Bird's-nest pudding, a pudding containing apples whose
cores have been replaced by sugar.
Yellow bird's nest, a plant, the Monotropa hypopitys.