The word 烦心 (fánxīn) is a compound formed through a straightforward modifier-head (or attributive-center) structure in Chinese morphology. The first character, 烦 (fán), carries the core meaning of "annoyed", "vexed", or "troublesome", and it acts as the modifier. The second character, 心 (xīn), means "heart" or "mind", and serves as the head noun. Literally, the combination means "a heart/mind that is troubled or annoyed". Therefore, the compound functions as either an adjective meaning "worrisome" or "distressing" (describing something that causes mental vexation) or as a stative verb meaning "to be worried" or "to be upset", directly describing the state of one's inner feelings being troubled.