Home › Words › F › fatnessfatness/ˈfætnəs/fatness means the state, quality, or condition of being fat.fatness is pronounced /ˈfætnəs/.EtymologyFrom Middle English fatnesse, fattenesse, from Old English fǣtnes (“fatness, the richest part of anything”), equivalent to fat + -ness.nounThe state, quality, or condition of being fat.Definitions & examples from Wiktionary (CC BY-SA 3.0).