It’s odd to notice, but once you do, it’s impossible to ignore. Every time a bank counter employee murmurs, “enter your PIN number,” a minor linguistic crime occurs. The acronym already includes the word “number.” Technically speaking, repeating it means saying “personal identification number number.” But hardly anyone recoils. Even the people who create these systems use the phrase because it has become so subtle in everyday speech.
The acronym is fairly straightforward. PINs, or personal identification numbers, are brief numerical codes that are used to confirm identity when conducting electronic transactions. It is typically four to six digits long and can be chosen by the customer at a branch counter, assigned by a bank, or sent in a sealed envelope that arrives days after the card. It’s a quiet ritual. The envelope, the scratch-off panel, the instant you commit a sequence to memory that you will use for years.
The technology underlying the PIN acronym, which is now widely understood, is not what makes it intriguing. It’s the way the phrase has become ingrained in common speech and developed a stubborn redundancy. This is known to linguists as RAS syndrome, short for Redundant Acronym Syndrome syndrome, a term that was winkingly coined in a 2001 New Scientist column. Similar phenomena can be found in “ATM machine,” “HIV virus,” and “SALT talks.” “Only the ultra-finicky would deplore them,” Bill Bryson once wrote. He’s got a point. Grammar guides don’t always describe how language behaves.
However, editors and writers feel that the repetition appears careless in print. No one is bothered by speech. It stands out in an official report. In discussions about acronyms, the conflict between language’s intended and actual functions frequently comes up, and PIN is among the best examples.
Most people are unaware of the multifaceted practical role of a PIN. The code opens a withdrawal at an ATM. A brief chain of approvals between the merchant, the acquiring bank, the processing network, and the issuing bank is initiated at the point of sale. An identity check takes a few seconds, sometimes even less. The buyer hardly notices. For tax filing, the IRS employs a six-digit version to guard against identity theft, a less common but growing use case.
Because PINs are so ingrained in daily life, it’s possible that the phrase “PIN number” is still redundant. More important than the term is the code. When you’re trying to remember which set of four digits corresponds with which card while standing in the rain at a gas pump, you don’t think about acronyms. All you do is type.
Additionally, there is a helpful distinction that should be remembered. A password is not the same as a PIN. Passwords frequently reside on distant servers, combine letters, numbers, and symbols, and are typically hashed or encrypted with more robust security. PINs are often stored locally on a device, are shorter, and are typically numerical. One is designed to move quickly. The other is designed to be deep. Both rely significantly on the user not selecting something obvious, such as a birthday, and have their own flaws.
The aging of the PIN acronym serves as a gentle reminder that language is rarely clean. The four letters were intended to be exact. They started talking to each other. And at some point, the additional “number” ceased to be an error and began to become a natural part of speech.
