waif

noun

1. 1.A castaway; a homeless child.
2. 2.(of a plant outside its native range) A plant that has been introduced but is not persistently naturalized.
3. 3.Goods found of which the owner is not known; originally, such goods as a pursued thief threw away to prevent being apprehended, which belonged to the king unless the owner made pursuit of the felon, took him, and brought him to justice.
4. 4.Hence, anything found, or without an owner; that which comes along, as it were, by chance.