bindexbackcross./bak-kraws, -kros/US // ˈbækˌkrɔs, -ˌkrɒs //UK // (ˈbækˌkrɒs) //溯源,溯溪,溯源活动,溯及既往Definitionsv.verb · 有主动词1.›to cross with either of its parents.n.noun · 名词1.›an instance of such crossing. Level 5More words in b →