Capitalization of acronyms
Acronyms are usually a shortened form derived from the initial letter of the words that make up the complete form.
Like all all-capital abbreviations, acronyms are usually written all in capitals and without periods. Unlike abbreviations, which are pronounced letter by letter (such as IRS), acronyms are pronounced as words.
Although the acronym is all in capital letters, the expanded form is not unless it refers to a proper noun.
AIDS acquired immune deficiency syndrome
PIN personal identification number
ZIP Zone Improvement Plan
SPELL Society for the Preservation of English Language and Literature
In a few cases, acronyms derived from initial letters are written entirely in small letters without periods. Typically, these are acronyms that have become accepted as a word in common usage.
laser light amplification by stimulated emission of radiation
scuba self-contained underwater breathing apparatus
Some coined names use more than the first letter of the word they represent. Such names are written with only the first letter capitalized if they represent a proper noun.
Amtrak American travel by track
radar radio detecting and ranging
Unusual abbreviations
Some abbreviations do not follow the usual pattern. Learn the most common exceptions.
pH
PhD
RPh
In some cases, an all-capital abbreviation may be spelled out. The spelled out forms are preferable when such abbreviations are used as verbs.
MC emcee master of ceremonies
DJ deejay disk jockey
The patient emceed a charity event prior to the accident.
(Rather than MC'd)
We okayed the patient for discharge.
(Rather than OK'd)
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