RAS syndrome

The term RAS syndrome refers to the use of one of the words that make up an initialism or acronym as well as the abbreviation itself, thus in effect repeating that word. It stands for "Redundant Acronym Syndrome syndrome," and is itself a humorous example of a redundant acronym.

Technically, this redundancy is a form of rhetorical tautology, and in many cases a pleonasm.

Origin
The term "RAS syndrome" was coined in 2001 by the New Scientist magazine. The term "PNS syndrome" ("PIN Number Syndrome syndrome," or "Personal Identification Number Number Syndrome syndrome"), coined by Usenet users, is used as commonly as RAS Syndrome, and in fact pre-dates the coining of "RAS Syndrome". Other nonce coinages continue to arise. The terms themselves are occasionally referred to as "RAP phrases" ("Redundant Acronym Phrases phrases").

Examples

 * ATM machine
 * Automated Teller Machine machine


 * HIV virus
 * Human Immunodeficiency Virus virus


 * PIN number
 * Personal Identification Number number.

Reasons for use
The linguistic explanation for RAS is that acronyms (such as laser) are treated as regular words (usually nouns), not as shorthand for longer phrases.

Some occurrences are in the interest of clarity; for example, when discussing a mainframe computer's requirements, the initialism "AC" might refer to air conditioning or alternating current depending on the context; the redundant phrase "AC current" is used by some to distinguish them, although the phrase "alternating current" is clear, correct, and not redundant. Also, the phrase "AC current" distinguishes from "AC voltage". The phrase "CSS style sheets" can also reduce ambiguity, where in certain contexts CSS could also refer to the content-scrambling system used on DVD video titles.

In the United Kingdom, most companies have their electrical appliances regularly checked for safety. This process is known as Portable Appliance Testing. However, it is almost universally abbreviated to "PAT testing". Presumably this is to avoid confusion with PA testing, or simply because it sounds a little ambiguous to say that one's occupation is "PAT". Sometimes similar phrases are not actually redundant; for example, a "redundant RAID" may in fact be a backup RAID in the system being described.

Acronyms and initialisms from foreign languages are also often analyzed as un-expandable nouns when they are not translated. For example, in French, "le protocole IP" (the IP protocol) is often used, and "HIV" is usually said either "le VIH" (in French, adjectives usually come after nouns) or "le virus HIV".

Another justification is that many acronyms and initialisms are trademarks, and trademark law generally treats trademarks as adjectives, which should be used with a generic noun. Examples of correct usage include "SPAM luncheon meat", "AIB Bank" and "CNN network".

Some speakers would prefer that the expansion of the acronym/initialism be used in situations where disambiguation or clarity is needed: "cascading style sheets" instead of "CSS style sheets", "alternating current" instead of "AC current", etc. However, some people may be more familiar with the acronym than the expansion, leading to potential for confusion.