Dictionary.com
Thesaurus.com

beach plum

American  

noun

  1. a shrub, Prunus maritima, of the rose family, of the seashores of northeastern North America, having sharply toothed leaves and white flowers.

  2. the purple or blackish edible fruit of this shrub.


beach plum British  

noun

  1. a rosaceous shrub, Prunus maritima , of coastal regions of E North America

  2. its edible plumlike fruit

"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 beach plum

An Americanism dating back to 1775–85