adjective, slap·hap·pi·er, slap·hap·pi·est. Informal.

severely befuddled; punch-drunk: a slaphappy boxer.
agreeably giddy or foolish: After a martini he was slaphappy.
cheerfully irresponsible: a slaphappy crowd.

Origin of slaphappy

First recorded in 1935–40; slap1 + happy Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for slap-happy


adjective -happier or -happiest informal

cheerfully irresponsible or careless
dazed or giddy from or as if from repeated blows; punch-drunk
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