The Greek word “harmos”

Found just once in the New Testament (Heb. 4:12), the Greek noun “harmos” meant “joint.”  God’s word is powerful enough to penetrate the innermost part of mankind.

In a citation from Westcott’s commentary on Hebrews the Dictionary of New Testament Theology (1:241) says:  “Absent from the LXX, the sole occurrence in NT is Heb. 4:12 where the scrutinizing power of ‘the word of God” is illustrated by the fact that it penetrates to the ‘most critical parts of the physical framework of man.’”