Strong's G2218 — ζυγός (noun)
zugos (dzoo-gos') n.
1. a coupling
2. (figuratively) servitude (a law or obligation)
3. (literally) the beam of the balance (as connecting the scales)
[from the root of zeugnumi "to join, especially by a yoke"]
KJV: pair of balances, yoke 
Occurrences: 6