triggered activity [trĭg′ərd] n. One or a series of spontaneously generated heartbeats originating from an action potential that produces an after-depolarization that reaches activation threshold. Liberaldictionary.com Is It Time For All Couples To Use The Term Partner? Can You Translate These Famous Phrases From Emoji? These Are the Longest Words in English These Are the Saddest Phrases in English The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.