The term 'undesirables' is used to refer to people who are considered to be undesirable or unwelcome in a particular society. This can include criminals, vagrants, and other people who are seen as a threat to the social order. The crossword solutions for this term are 'RIFFRAFF' (8 letters), 'scums' (5 letters), and 'tares' (5 letters). RIFFRAFF is a derogatory term used to describe people of low social standing, while scums and tares are both terms used to describe people who are considered to be morally corrupt or dangerous. All three words are used to describe people who are seen as undesirable in a particular society.