This has been around for a long, long time. According to Etymonline,
et cetera also etcetera, early 15c., from L. et cetera, lit. "and the others," from et "and" + neut. of ceteri "the others." The common abbreviation was &c. before 20c., but etc. now prevails.
Normally people will say "and so on" or "and so forth" when speaking, but plenty of times you will hear "et cetera."
In the 19th and early 20th centuriesy the one-word version, etcetera (or etceteras) was used as a synonym for sundries or odds and ends, and Webster's 3rd New Int'l. Dictionary cites Elizabeth Bowen (who consorted with the Bloomsbury group) using it in a sentence. So it must have had some currency before The King and I.