Dictionary.com
Thesaurus.com

pussy willow

American  
[poos-ee] / ˈpʊs i /

noun

  1. a small willow, Salix discolor, of eastern North America, having silky catkins.

  2. any of various similar willows.


pussy willow British  
/ ˈpʊsɪ /

noun

  1. a willow tree that produces silvery silky catkins, esp Salix caprea or S. cinerea in Britain or S. discolor in North America

  2. any of various similar willows

"Collins English Dictionary — Complete & Unabridged" 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Etymology

Origin of pussy willow

An Americanism dating back to 1865–70