Etymology From Middle English garisoun, garysoun, from Old French garison, guarison, from guarir + -ison, ultimately of Germanic origin; thus a doublet of warison. Compare guard, ward; the modern meaning is influenced by (now obsolete) garnison.
1
A permanent military post.
2
The troops stationed at such a post.
My Lord the great Commander of the worlde, […] Hath now in armes ten thouſand Ianiſaries, […] And for the expedition of this war, If he thinke good, can from his garriſons, UUithdraw as many more to follow him.c. 1587–1588 (date written), [Christopher Marlowe], Tamburlaine the Great. […] The First Part […], 2nd edition, part 1, London: […] [R. Robinson for] Richard Iones, […], published 1592, →OCLC; reprinted as Tamburlaine the Great (A Scolar Press Facsimile), Menston, Yorkshire; London: Scolar Press, 1973, →ISBN, Act III, scene iii:
For a time, it was the only Royalist stronghold between London and Exeter, but it fell at last when a member of the garrison turned traitor and admitted the Parliamentary besiegers who destroyed it with gunpowder.1980, AA Book of British Villages, Drive Publications Ltd, page 134, about Corfe Castle:
3
Occupants.
“I came down like a wolf on the fold, didn’t I ? Why didn’t I telephone ? Strategy, my dear boy, strategy. This is a surprise attack, and I’d no wish that the garrison, forewarned, should escape. …”1913, Robert Barr, chapter 4, in Lord Stranleigh Abroad:
4
Government, Military, Politics, WarSpace Force, US A military unit, nominally headed by a colonel, equivalent to a USAF support wing, or an army regiment.
Etymology From Middle English garisoun, garysoun, from Old French garison, guarison, from guarir + -ison, ultimately of Germanic origin; thus a doublet of warison. Compare guard, ward; the modern meaning is influenced by (now obsolete) garnison.
1
To assign troops to a military post.
Nor was he content with thus strongly garrisoning the fort, but he likewise added exceedingly to its strength by furnishing it with a formidable battery of quaker guns—rearing a stupendous flag-staff in the centre which overtopped the whole city—and moreover by building a great windmill on one of the bastions.1809, Diedrich Knickerbocker [pseudonym; Washington Irving], chapter III, in A History of New York, from the Beginning of the World to the End of the Dutch Dynasty. […], volume I, New York, N.Y.: Inskeep & Bradford, […], →OCLC, book IV, page 216:
2
To convert into a military fort.
3
To occupy with troops.
'Establishing a land bridge through Mariupol to Crimea would take tens of thousands of troops. So would garrisoning eastern Ukraine.', http://www.economist.com/news/briefing/21615605-now-willing-use-russian-troops-more-or-less-openly-eastern-ukraine-vladimir-putin-has