From BiblePortal Wikipedia

Webster's Dictionary [1]

(1): ( n.) Alt. of Defence

(2): ( v. t.) To furnish with defenses; to fortify.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [2]

This word, besides its ordinary and proper use, stands in the English Bible as a mistranslation of two Heb. terms. 1.' Matsotr מָצוֹר , in connection with יְאֹרַים , streams, rendered in  2 Kings 19:24, "rivers of besieged places," Sept. Ποταμοι Συνοχῆς , Vulg. Aquae Clausae ; in  Isaiah 19:6, "brooks of defense," Sept. Διώρυες Τοῦ Ποταμοῦ , Vulg. Rivi Aggerum ; in  Isaiah 37:25, "rivers of the besieged places," Sept. Συναγωγὴ Ὕδατος , Vulg. Rivi Aggerum ), a proper name for Egypt alluding to its canals, i.e. the branches of the Nile. The derivation of the term is obscure; perhaps it is only another application of the Heb. word of the same form, elsewhere signifying (literally straitness, hence) a mound or fortification, and applied to Egypt, especially Lower Egypt, as being strongly fortified, both by nature and art. (See Mazor).

2. Be'Tser ( בֶּצֶר , probably something dug out of a mine, occurring only in Job, and rendered in chap. 22:24, "gold," Sept. Πέτρα , Vulg. Silex ; in  Isaiah 37:25, "defense," Sept. Βοηθὸς Ἀπὸ Ἐχθρῶν , Vulg. Contra Hostes ; in chap. 36:19, gold," Sept. Δυνατὸς Ἐν Ἀνάγκῃ , Vulg. Tribulatio ), precious ore, i.e. of gold or silver, in its native state; an interpretation evidently required by the corresponding terms in the parallel members of the hemistichs where it occurs. (See Gold).