The Collaborative International Dictionary of English v.0.48:
Willow \Wil"low\, n. [OE. wilowe, wilwe, AS. wilig, welig; akin
to OD. wilge, D. wilg, LG. wilge. Cf. Willy.]
1. (Bot.) Any tree or shrub of the genus Salix, including
many species, most of which are characterized often used
as an emblem of sorrow, desolation, or desertion. "A
wreath of willow to show my forsaken plight." --Sir W.
Scott. Hence, a lover forsaken by, or having lost, the
person beloved, is said to wear the willow.
And I must wear the willow garland
For him that's dead or false to me. --Campbell.
2. (Textile Manuf.) A machine in which cotton or wool is
opened and cleansed by the action of long spikes
projecting from a drum which revolves within a box studded
with similar spikes; -- probably so called from having
been originally a cylindrical cage made of willow rods,
though some derive the term from winnow, as denoting the
winnowing, or cleansing, action of the machine. Called
also willy, twilly, twilly devil, and devil.
Almond willow, Pussy willow, Weeping willow. (Bot.) See
under Almond, Pussy, and Weeping.
Willow biter (Zool.) the blue tit. [Prov. Eng.]
Willow fly (Zool.), a greenish European stone fly
(Chloroperla viridis); -- called also yellow Sally.
Willow gall (Zool.), a conical, scaly gall produced on
willows by the larva of a small dipterous fly (Cecidomyia
Willow grouse (Zool.), the white ptarmigan. See
Willow lark (Zool.), the sedge warbler. [Prov. Eng.]
Willow ptarmigan (Zool.)
(a) The European reed bunting, or black-headed bunting.
See under Reed.
(b) A sparrow (Passer salicicolus) native of Asia,
Africa, and Southern Europe.
Willow tea, the prepared leaves of a species of willow
largely grown in the neighborhood of Shanghai, extensively
used by the poorer classes of Chinese as a substitute for
Willow thrush (Zool.), a variety of the veery, or Wilson's
thrush. See Veery.
Willow warbler (Zool.), a very small European warbler
(Phylloscopus trochilus); -- called also bee bird,
haybird, golden wren, pettychaps, sweet William,
Tom Thumb, and willow wren.