underseal
(Brit) (US undercoat) n [U]
tar-like or rubber-like substance used to protect the under-side of a motor vehicle against rust, etc (机动车底部的)防蚀涂层. underseal, v [Tn] coat the under-side of (a motor vehicle, etc) with a protective seal 用防蚀涂层涂(机动车等)的底部.