"building where horses or cows are kept," mid-13c., "building for domestic animals," from O.Fr. estable "a stable, stall" (also applied to cowsheds and pigsties), from L. stabulum "a stall, fold, aviary, etc." lit. "a standing place," from stem of stare "to stand" (see stet). Meaning "collection of horses belonging to one stable is attested from 1570s; transferred sense of "group of fighters under same management" is from 1897; that of "group of prostitutes working for the same employer" is from 1937.
"For what the grete Stiede
Is stole, thanne he taketh hiede,
And makth the stable dore fast."
[John Gower, "Confessio Amantis," 1390]
"steadfast, firm," c.1275, from O.Fr. estable, from L. stabilis "firm, steadfast," lit. "able to stand," from stem of stare "to stand" (see stet). Physical sense of "secure against falling" is recorded from c.1300. Of nuclear isotopes, from 1904.