測定
そくてい · sokutei · JLPT N2 · noun
measurement
📏 測 = measure + 定 = fix or settle: measure and fix the exact value (sokutei)
測 (measure) and 定 (set, settle) combine to mean measuring something and pinning down its exact value. The same pattern appears in 測定器 (measuring instrument).
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.'