ILL is a realistic first-person action horror game that takes you into a dark fort overtaken by a mysterious entity. A grim story, unpredictable monsters, a visceral dismemberment system, and ... ILL is a realistic first-person action horror game that takes you into a dark fort overtaken by a mysterious entity. Unpredictable monsters, a visceral disme... Learn the meaning, pronunciation and usage of the adjective ill, which can mean suffering from an illness or disease, or bad or harmful. See examples, idioms, collocations and word origin of ill. Ill definition: of unsound physical or mental health; unwell; sick.. See examples of ILL used in a sentence.