undesirable

(noun) one whose presence is undesirable. Example: "Rounding up vagrants and drunks and other undesirables."

(adj) not wanted. Synonyms: undesirable (vs. desirable), unwanted. Examples: "Undesirable impurities in steel." "Legislation excluding undesirable aliens";"removed the unwanted vegetation."

(adj) not worthy of being chosen (especially as a spouse). Synonyms: unsuitable.