To whom is the arm of the Lord revealed?
Isa. lii. 1.

Arm's end, the end of the arm; a good distance off. Dryden. -- Arm's length, the length of the arm. -- Arm's reach, reach of the arm; the distance the arm can reach. -- To go (or walk) arm in arm, to go with the arm or hand of one linked in the arm of another. "When arm in armwe went along." Tennyson. -- To keep at arm's length, to keep at a distance (literally or figuratively); not to allow to come into close contact or familiar intercourse. -- To work at arm's length, to work disadvantageously.

And make him with our pikes and partisans
A grave: come, arm him.
Shak.

Arm your prize;
I know you will not lose him.
Two N. Kins.

His shoulders broad and strong,
Armed long and round.
Beau. *** Fl.

Abram . . . armed his trained servants.
Gen. xiv. 14.

Arm yourselves . . . with the same mind.
1 Pet. iv. 1.

To arm a magnet, to fit it with an armature.