past master noun
plural ∼ -ters [count] : a person who has done something many times before and has become very skilled at doing it : expert
▪ He's a past master at finding ways to get out of trouble. ▪ They are past masters of the art of propaganda.
▪ He's a past master at finding ways to get out of trouble. ▪ They are past masters of the art of propaganda.
