Heb. matstsab, a station; a place where one stands (1 Samuel 14:12); a military or fortified post (1 Samuel 13:23; 14:1,4,6, etc.).
Heb. netsib, a prefect, superintendent; hence a military post (1 Samuel 10:5; 13:3,4; 2Sam 8:6). This word has also been explained to denote a pillar set up to mark the Philistine conquest, or an officer appointed to collect taxes; but the idea of a military post seems to be the correct one.
Heb. matstsebah, properly a monumental column; improperly rendered pl. "garrisons" in Ezekiel 26:11; correctly in Revised Version "pillars," marg. "obelisks," probably an idolatrous image.
Source: Easton's Bible Dictionary
Garrison
GAR'RISON, n. English, garnish; warren, and from this root we have warrant and guaranty, as well as guard and regard, all from one source.
1. A body of troops stationed in a fort or fortified town, to defend it against an enemy, or to keep the inhabitants in subjection.
2. A fort, castle or fortified town, furnished with troops to defend it.
3. The state of being placed in a fortification for its defense; as troops laid in garrison.
GAR'RISON, v.t. To place troops in a fortress for its defense; to furnish with soldiers; as, to garrison a fort or town.
1. To secure or defend by fortresses manned with troops; as, to garrison a conquered territory.
Source: King James Dictionary
Garrison
The Hebrew words so rendered in the Authorized Version are derivatives from the root natsab , to "place, erect," which may be applied to a variety of objects.
Mattsab and mattsabah undoubtedly mean a "garrison" or fortified post. (1 Samuel 13:23; 14:14; 1 Samuel 15; 2 Samuel 23:14)
Netsib is also used for a "garrison" in (1 Chronicles 11:16) but elsewhere for a "column" erected in an enemy’s country as a token of conquest. (1 Samuel 13:3)
The same word elsewhere means "officers" placed over a vanquished people. (2 Samuel 8:6,14; 1 Chronicles 18:13; 2 Chronicles 17:2)
Mattsebah in (Ezekiel 26:11) means a "pillar."