deutero-

before vowels deuter-, word-forming element meaning "second," from Late Latin deutero-, from Greek deuteros "next, second," a word of uncertain origin. According to some sources from duo "two" (from PIE root *dwo- "two"), but according to Watkins the ground sense is "missing" and the Greek word is from PIE *deu-tero-, suffixed form of *deu- (1) "to lack, be wanting." But Beekes doubts even this.