密封底部；底封；
1. 底封：undersea delta 潜三角洲 | underseal 底封 | underseepage cutoff 洛渗截留
2. 防蚀涂层 底封：undersea /海面下的/在海面下/ | underseal /防蚀涂层/底封/ | underseas /海面下的/
3. underseal
3. 封闭腻子：undergroundwater 地下水 | underseal 封闭腻子 | undertone 面色薄层正视;底色薄层背光平视;淡色
4. 密封：underseacable 海底电缆 | underseal 密封 | underseal 密封
noun
1. seal consisting of a coating of a tar or rubberlike material on the underside of a motor vehicle to retard corrosion
Synonym: undercoat