Meaning

noun the sound made by a gentle blow

noun a light touch or stroke

verb pat or squeeze fondly or playfully, especially under the chin

originFrom Middle English *patten, alteration (with loss of medial l) of platten, pletten (“to pat”), from Old English plættan (“to buffet, strike, slap, smack, give a sounding blow”), from Proto-West Germanic *plattjan, from Proto-Germanic *plat- (“to strike, beat”), from Proto-Indo-European *blod-, *bled- (“to strike, beat”). Cognate with Middle Dutch platten, pletten (“to strike, bruise, crush,…

Etymology from Wiktionary, CC BY-SA 3.0