POWER, strength, capacity — the general word, paired at Zechariah 4:6 with the sharper-edged chayil ('not by chayil, and not by koach, but by my spirit'). Where chayil leans military — an army, a force fielded — koach is ability itself: the power to act, to stand, to accomplish, with no particular weapon implied. Samson's koach is in his hair (Judges 16:5, not yet on these pages); a sick man's koach fails him (Psalm 71:9). Pairing the two words at Zechariah 4:6 covers the whole field of human capability, military and otherwise, and denies Zerubbabel both at once. → first discussed at Zechariah 4:6