Meaning

adjective affected by an impairment of normal physical or mental function

adverb (`ill' is often used as a combining form) in a poor or improper or unsatisfactory manner; not well

noun an often persistent bodily disorder or disease; a cause for complaining

originFrom Middle English ille (“evil; wicked”), from Old Norse íllr (adjective), ílla (adverb), ílt (noun), from Proto-Germanic *ilhilaz, from Proto-Indo-European *h₁elḱ- (whence Latin ulcus (“sore”), Ancient Greek ἕλκος (hélkos, “wound, ulcer”), Sanskrit अर्शस् (árśas, “hemorrhoids”)). Cognates Cognate with Scots and Yola ill, Danish ilde (“bad”), Faroese, Icelandic illur (“bad, ill, wicked”),…

Etymology from Wiktionary, CC BY-SA 3.0