ill (adj.) Look up ill at
c. 1200, "morally evil; offensive, objectionable" (other 13c. senses were "malevolent, hurtful, unfortunate, difficult"), from Old Norse illr "evil, bad; hard, difficult; mean, stingy," a word of unknown origin. Not considered to be related to evil. From mid-14c. as "marked by evil intentions; harmful, pernicious." Sense of "sick, unhealthy, diseased, unwell" is first recorded mid-15c., probably from a use similar to that in the Old Norse idiom "it is bad to me." Slang inverted sense of "very good, cool" is 1980s. As a noun, "something evil," from mid-13c.
ill (v.) Look up ill at
early 13c., "do evil to," from ill (adj.). Meaning "speak disparagingly" is from 1520s. Related: Illed; illing.
ill (adv.) Look up ill at
c. 1200, "wickedly; with hostility," from ill (adj.). Meaning "not well, poorly" is from c. 1300. It generally has not shifted to the realm of physical sickess, as the adjective has done. Ill-fated recorded from 1710; ill-informed from 1824; ill-tempered from c. 1600; ill-starred from c. 1600. Generally contrasted with well, hence the useful, but now obsolete or obscure illcome (1570s), illfare (c. 1300), and illth.