-ster
suff 後缀 (with ns and adjs forming ns 与名词和形容词结合构成名词) person connected with or having the quality of 与...有关的人; 有...品性的人
gangster * prankster * youngster.
and there is a very firm rule that the bank has no right or authority to pay out a customer's money on a cheque on which its customer's signature has been forged.