- variant of quadri-.
Origin of quadru-
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for quadru-
word-forming element meaning "four, having four, consisting of four," variant of quadri-, especially before -p-, from an older form of the element, which perhaps was influenced later by tri-.
Online Etymology Dictionary, © 2010 Douglas Harper