1530, replacing earlier steadfast, from stead + adj. suffix -y, perhaps on model of M.Du., M.L.G. stadig. O.E. had stæððig "grave, serious," and stedig "barren," but neither seems to be the direct source of the modern word. O.N. cognate stoðugr "steady, stable" was closer in sense. Originally of things; of persons or minds from 1602. Meaning "working at an even rate" is first recorded in 1548. The verb also is first recorded 1530. Noun meaning "one's boyfriend or girlfriend" is from 1897; to go steady is 1905 in teenager slang. Steady progress is etymologically a contradiction in terms. Steady state first attested 1885; as a cosmological theory (propounded by Bondi, Gold, and Hoyle), it is attested from 1948.
late 15c., from Fr. béguine (13c.), M.L. beguina, a member of a women's spiritual order said to have been founded c.1180 in Liege in the Low Countries. They are said to take their name from the surname of Lambert le Bègue "Lambert the Stammerer," a Liege priest who was instrumental in their founding, and it's likely the word was pejorative at first. The order generally preserved its reputation, though it quickly drew imposters who did not; nonetheless it eventually was condemned as heretical. A male order, called Beghards founded communities by the 1220s in initation of them, but they soon degenerated (cf. O.Fr. beguin "(male) Beguin," also "hypocrite") and wandered begging in the guise of religion; they likely were the source of the words beg and beggar, though there is disagreement over whether Beghard produced M.Du. beggaert "mendicant" or was produced by it. Cole Porter's "Begin the Beguine" (1935) refers to a kind of popular dance, from French colloquial béguin "an infatuation, boyfriend, girlfriend," earlier "child's bonnet," and before that "nun's headdress" (14c.).