Concise Bible Dictionary:
The member of the body which is capable of lifting burdens and defending the person: it is used symbolically for the power and strength of God on behalf of His saints (Ex. 15:16; Psa. 77:15; Isa. 51:9; Isa. 53:1). The arm of Jehovah is often spoken of in the Old Testament It redeemed (Ex. 6:6); gathers His own (Isa. 40:11); and rules for Him (Isa. 40:10), as in the kingdom. It is a holy arm (Isa. 52:10; Psa. 98:1); and it is a glorious arm (Isa. 63:12). The arm of the Lord is revealed to souls where there is repentance and faith in the report which God sends (Isa. 53:1; Rom. 10:16). It is to be trusted in even by the isles of the Gentiles, that is, by sinners everywhere in creation (Isa. 51:5).
Strong’s Dictionary of Greek Words:
Transliteration:
brachion
Meaning:
properly, comparative of 1024, but apparently in the sense of βράσσω (to wield); the arm, i.e. (figuratively) strength