caperberry
From The Oxford Companion to Spirits & Cocktails
, the fruit of the caper bush, generally sold pickled in brine, is sometimes used in place of the more conventional olive as a garnish in cocktails such as the Martini. See Martini.
This definition is from The Oxford Companion to Spirits & Cocktails, edited by David Wondrich (Editor-in-Chief) and Noah Rothbaum (Associate Editor).