a combining form meaning “billion,” used in the formation of compound words: gigabyte.

Origin of giga-

From the Greek word gígās giant Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2020

British Dictionary definitions for giga-

/ (ˈɡɪɡə, ˈɡaɪɡə) /

combining form

denoting 10 9gigavolt Symbol: G
(in computer technology) denoting 2 30gigabyte

Word Origin for giga-

from Greek gigas giant
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

Medical definitions for giga-



One billion (109):gigahertz.
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for giga-


A prefix that means:
One billion (109), as in gigahertz, one billion hertz.
230 (that is, 1,073,741,824), which is the power of 2 closest to a billion, as in gigabyte.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.