礼
れい · rei · JLPT N3 · noun
gratitude
🙇 礼 = 礻 altar radical + a kneeling figure: you bow at the altar
The left part 礻 is the altar/spirit radical, which shows up in words about ritual. The older form 禮 adds 豊, a vessel full of offerings. So 礼 means proper ritual conduct, and from that come a bow (お礼) and thanks. Say it rei, like a ray.
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.