loathsome UK /ˈləʊð.səm/US /ˈloʊð.səm/ adjective1 •Highly offensive; abominable, sickening.Come on my Lords the better foot before, / Straight vvill I bring you to the lothsome pit, / VVhere I espied the Panther fast a sleepe. — 1588 formsmore loathsome · most loathsome