RAS syndrome (short for "redundant acronym syndrome syndrome"), also known as PNS syndrome ("PIN number syndrome syndrome", which expands to "personal identification number number syndrome syndrome") or RAP phrases ("redundant acronym phrase phrases"), refers to the use of one or more of the words that make up an acronym or initialism in conjunction with the abbreviated form, thus in effect repeating one or more words. Examples include "PIN number", which may be expanded as "personal identification number number". A person is humorously said to suffer from RAS syndrome when he or she redundantly uses one or more of the words that make up an acronym or initialism with the abbreviation itself. Usage commentators consider such redundant acronyms poor style and an error to be avoided in writing, though they are common in speech.