Word Origin a combining form meaning “breast,” used in the formation of compound words: mastopathy.
especially before a vowel
Origin of masto-
combining form representing
Greek mastós breast
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
British Dictionary definitions for masto- masto- before a vowel mast- indicating the breast, mammary glands, or something resembling a breast or nipple mastodon; mastoid Word Origin for masto-
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
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Word Origin and History for masto-
mast-, word-forming element meaning "breast," from comb. form of Greek mastos "woman's breast," from madan "to be wet, to flow," from PIE *mad- "wet, moist, dripping" (cf. Latin madere "be moist;" Albanian mend "suckle;" see mast (n.2)).
Online Etymology Dictionary, © 2010 Douglas Harper
Breast; mammary gland; nipple: mastectomy.
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.