失礼
しつれい · shitsurei · JLPT N4 · noun
disrespect
失礼 = lose (失) + manners (礼): manners lost, so rudeness
失 means to lose or slip; 礼 means courtesy, as in お礼 (thanks). Saying 失礼します literally admits I am about to lose my manners, which is why it works as Excuse me when entering, leaving, or interrupting.
礼 — 示 (altar/ritual) + 乚 (simplified from 豊)
Originally 禮, showing 示 (altar) beside 豊 (a ritual vessel of grain), depicting offerings made at a shrine. The character meant religious ceremony, then broadened to social rites, courtesy, and gifts. The simplified form 礼 keeps 示 and replaces 豊 with the abbreviated 乚.