stately adj.

suffix forming adjectives from nouns and meaning "having qualities of, of the form or nature of" (manly, lordly), "appropriate to, fitting, suited to" (bodily, earthly, daily); irregularly descended from Old English -lic, from Proto-Germanic *-liko- (Old Frisian -lik, Dutch -lijk, Old High German -lih, German -lich, Old Norse -ligr), related to *likom- "appearance, form" (Old English lich "corpse, body;" see lich, which is a cognate; see also like (adj.), with which it is identical).

c. 1200, "circumstances, position in society, temporary attributes of a person or thing, conditions," from Old French estat "position, condition; status, stature, station," and directly from Latin status "a station, position, place; way of standing, posture; order, arrangement, condition," figuratively "standing, rank; public order, community organization," noun of action from past participle stem of stare "to stand" from PIE root *sta- "to stand, make or be firm." Some Middle English senses are via Old French estat (French état; see estate).

The Latin word was adopted into other modern Germanic languages (German, Dutch staat) but chiefly in the political senses only. Meaning "physical condition as regards form or structure" is attested from late 13c. Meaning "mental or emotional condition" is attested from 1530s (phrase state of mind first attested 1749); colloquial sense of "agitated or perturbed state" is from 1837.

He [the President] shall from time to time give to the Congress Information of the State of the Union, and recommend to their Consideration such Measures as he shall judge necessary and expedient. [U.S. Constitution, Article II, Section iii]

also state-room, 1703, room reserved for ceremonial occasions; earlier (1650s) "a captain's cabin;" from room (n.) + state (n.1) in a sense also preserved in stately.