水すい密みつ扉とびらMeanings1nounwatertight doorTechnical term used in maritime, engineering, and construction contexts for a door designed to prevent water from passing through.船ふねの水すい密みつ扉とびらは、浸しん水すいを防ふせぐために閉しめておく必ひつ要ようがある。The ship's watertight doors must be kept closed to prevent flooding.