The same as matsowr in the sense of a limit; Egypt (as the border of Palestine) -- besieged places, defense, fortified.
see HEBREW matsowr
H4693. Matsor
מָצוֺר proper name, of a territory = מִצְרַיִם; only in poetry: מ ׳יֶאֹרֵי Isaiah 19:6; 2 Kings 19:24 = Isaiah 37:25; מ וְעָרֵי ׳אַשּׁוּד מ ׳וּלְמִנִּי נָהָר וְעַד לְמִנִּי יָבוֺא וְעָדֶיךָ Micah 7:12 (ᵐ5 misunderstands everywhere).