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definitions

mast-

variant of masto- before a vowel: mastectomy.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for mast-

mast-

combining form

a variant of masto-
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
mast- in Medicine

mast-

pref.

Variant ofmasto-
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.