主演
しゅえん · shuen · JLPT N1 · noun
playing the leading part
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.
演 — water 氵 + 寅 (yín, phonetic)
演 is a semantic-phonetic compound: the water radical 氵 gives the meaning, originally referring to water flowing far and spreading out, while 寅 supplies the sound. From 'water extending' it broadened to 'develop, elaborate, perform,' as in unfolding a story or acting out a play.