See more synonyms for misspeak on Thesaurus.com
verb (used with or without object), mis·spoke, mis·spok·en, mis·speak·ing.
  1. to speak, utter, or pronounce incorrectly.
  2. to speak inaccurately, inappropriately, or too hastily.

Origin of misspeak

1150–1200; Middle English misspeken; see mis-1, speak; compare Old English missprecan to murmur
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

Word Origin and History for misspeak

late 14c., "to say amiss," also "to speak insultingly," from mis- (1) + speak. Related: Misspeaking; misspoken. Old English missprecan meant "to grumble, murmur."

Online Etymology Dictionary, © 2010 Douglas Harper