a combining form meaning “four,” used in the formation of compound words: tetrabranchiate.
Also especially before a vowel, tetr-.
Origin of tetra-
< Greek, combining form of téttara, neuter of téttares four
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
before a vowel tetr-
Word Origin for tetra-
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
word-forming element meaning "four," from Greek tetra-, combining form of tettares, tessares "four" (see four).
Online Etymology Dictionary, © 2010 Douglas Harper
Composed of or containing four atoms, molecules, or groups:tetrasaccharide.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.