Origin: Latin suffix -able
Undesirable has 5 different meanings across 2 categories:
one whose presence is undesirable
"rounding up vagrants and drunks and other undesirables"
an undesirable person.
"The security guard immediately flagged him as an undesirable person and stopped him from entering the building."
not wanted
"undesirable impurities in steel"
"legislation excluding undesirable aliens"
"removed the unwanted vegetation"
not worthy of being chosen (especially as a spouse)
"After three failed dates, he finally admitted that meeting someone from his family's social circle was becoming an undesirable option for finding a wife."
objectionable or not likely to please
"The manager immediately removed the undesirable candidate from the interview list after they insulted the hiring committee during their first meeting."