厳密
げんみつ · genmitsu · JLPT N1 · na-adj
strict
厳 = strict + 密 = dense/tight: strictly tight, leaving no gaps
厳 means severe or strict, and 密 means dense or close-fitting. Together they describe rules or measurements with no slack, so げんみつ means strict or precise.
密 — 宀 roof + 必 (phonetic) + 山 mountain
Originally referring to a hidden, sheltered place in the mountains, 密 combines 宀 (roof/cover) over 必 (phonetic) with 山 (mountain) at the base. The meaning extended from 'secluded mountain hideaway' to 'dense, close, secret'. Today it commonly means dense, intimate, or secret.