The Aramaic word edra (H153) means "arm" and by extension "strength" or "power." It appears in Daniel 2:32 in the description of Nebuchadnezzar's statue: "its chest and arms of silver." The word is cognate with Hebrew zeroa (H2220).
In Semitic languages, the arm (edra/zeroa) is the primary metaphor for power, military strength, and the ability to act decisively.
In Daniel's vision, the silver arms and chest of the statue represent the Medo-Persian empire — vast, powerful, spanning both East and West. Yet even the mightiest arms of human empire are temporary; they too will be crushed by the stone cut without hands.
The theological contrast runs throughout Scripture: the arm of flesh fails (2 Chronicles 32:8), but the arm of the LORD is eternally mighty. "The LORD has made bare his holy arm before the eyes of all the nations, and all the ends of the earth shall see the salvation of our God" (Isaiah 52:10). True power belongs to God alone.