主要
しゅよう · shuyou · JLPT N3 · na-adj
main
👑 主要 = master (主) + essential (要): the master essential, i.e. the main one
主 means master or chief, as in 主人 (master, host). 要 means essential or needed, as in 重要 (important) and 必要 (necessary). Put together, the chief essential thing is the main one. Sound hook: shuyou is close to sure, you — sure, you are the main one.
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.
要 — west 覀 (top) + woman 女 (bottom)
Originally a pictograph of a woman with hands on her waist, meaning 'waist' (the original form of 腰). The top 覀 is a stylized depiction of the waist area, not the character for 'west'. Over time it was borrowed for the meaning 'to want, important', so 腰 (with 月 flesh radical) was created for the original 'waist' sense.