illustrious

From Latin illūstris (“bright, shining; distinguished, prominent, illustrious”) + -ous (suffix forming adjectives from nouns, to denote possession or presence of a quality in any degree). Illūstris is derived from illūstrō (“to brighten, illuminate; to make famous or illustrious”), from in- (“in, inside”) + lūstrō (“to purify by making a sacrifice; to brighten, illuminate”) (from lūstrō (“purificatory sacrifice”), possibly ultimately from Proto-Indo-European *lewk- (“bright; to shine”) or *lewh₃- (“to wash”)).