if something is customary, it is what people usually do in a particular place or situation 习俗的；习惯的 typical of a particular person （某人）特有的，独特的，典型的
Word Originlate Middle English (as a noun): from medieval Latin custumarius, from custuma, from Anglo-Norman French custume from Old French coustume, based on Latin consuetudo, from consuetus, past participle of consuescere ‘accustom’, from con- (expressing intensive force) + suescere ‘become accustomed’.