予定
よてい · yotei · JLPT N4 · noun
plan
📅 予定 = beforehand (予) + fix/decide (定): what's fixed in advance
予 means in advance, as in 予約 (reservation) and 予報 (forecast). 定 means to settle or fix, as in 決定 (decision). So yotei is literally something settled ahead of time: a plan or schedule. Sound hook: yo, tei (they) already decided.
定 — roof 宀 + 正 (correct/upright, phonetic)
Originally written with 宀 (roof) over 正 (upright/correct), suggesting a household settled and orderly under its roof. Over time 正 simplified to 㐬-like form at the bottom, and the meaning shifted from 'settled home' to the broader senses of 'fix, stable, decide.'