WordNet (r) 3.0 (2006):
personal identification number n 1: a number you choose and use to gain access to various accounts [syn: personal identification number, PIN, PIN number]The Free On-line Dictionary of Computing (30 December 2018):
Personal Identification Number PIN(PIN, "PIN number") A password, typically four digits entered through a telephone keypad or automatic teller machine. (1996-11-03)