smartmouth

noun informal

a witty or sarcastic person

witty or sarcastic comments

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 Origin and History for smartmouth

1968, from smart (adj.) + mouth (n.).