stable (n.) Look up stable at Dictionary.com
early 13c., "building or enclosure where horses or cows are kept, building for domestic animals," from Old French stable, estable "a stable, stall" (Modern French étable), also applied to cowsheds and pigsties, from Latin stabulum "a stall, fold, aviary, beehive, lowly cottage, brothel, etc.," literally "a standing place," from PIE *ste-dhlo-, suffixed form of root *sta- "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]
stable (adj.) Look up stable at Dictionary.com
mid-12c., "trustworthy, reliable;" mid-13c., "constant, steadfast; virtuous;" from Old French stable, estable "constant, steadfast, unchanging," from Latin stabilis "firm, steadfast, stable, fixed," figuratively "durable, unwavering," literally "able to stand," from PIE *ste-dhli-, from root *sta- "to stand" (see stet). From c.1300 as "well-founded, well-established, secure" (of governments, etc.). Physical sense of "secure against falling" is recorded from late 14c.; also "of even temperament." Of nuclear isotopes, from 1904.
stable (v.) Look up stable at Dictionary.com
"to put in a certain place or position," c.1300; "to put (a horse) in a stable," early 14c., from stable (n.) or from Old French establer. Related: Stabled; stabling.