主力
zhǔlì · HSK 7
main force
💪 主力 = 主 (main) + 力 (force/strength) = the main force
主 means main or master; 力 means force or strength. Stacked together they name the backbone of a group — the core strength that bears the brunt of the work.
主 — flame/lamp on top of a stand 王
Originally a pictograph of a lamp with a flame on top of its stand, representing the lord or master of the household who tended the fire. The meaning extended from 'lamp/host' to 'master, owner, main, principal'. The character 炷 (wick) preserves the original 'lamp' sense.
力 — pictograph of a plow or arm muscle
力 originated as a pictograph of an ancient plow, the main tool requiring physical exertion in early agriculture. Some scholars also see it as a flexed arm showing muscle. From this concrete image it broadened to mean 'strength, power, force, effort'.