Waif

trẻ bơ vơ

(person (especially a child) who is homeless and without means of support)

trẻ bị bỏ rơi

(person (especially a child) who is homeless and without means of support)

vật vô chủ

(article of movable property found of which the owner is not known)

vật vô chủ

(something found, especially if without an owner)