The term 'thieving sort' is used to describe a type of criminal who engages in theft and other related activities. The two crossword solutions for this term are 'CROOK' (5 letters) and 'STEALER' (7 letters). Both words refer to someone who steals or commits other illegal acts, but 'CROOK' is more commonly used to describe a professional criminal, while 'STEALER' is more often used to describe someone who engages in petty theft.