Dictionary.com
Thesaurus.com

whitten

American  
[wit-n, hwit-] / ˈwɪt n, ˈʰwɪt- /

noun

British.
  1. any of several trees or shrubs having clusters of white flowers, such as the guelder rose, mountain ash, or wayfaring tree.


Etymology

Origin of whitten

First recorded in 1665–75; ultimately from Old English hwītingtrēow “whitten tree,” from hwīt white ( def. ) + -ing -ing 3 ( def. ) + trēow tree ( def. )