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April 12, 2012

Using "a" or "an" With Acronyms and Abbreviations

Nyarinby Jeff Hume-Pratuch

Dear Style Experts,

How do you tell whether to use a or an with abbreviations? I assume that an abbreviation is treated just as if it were a word , but I'm having trouble with some examples: Should it be an HIV patient or a HIV patient? For some reason, neither one looks right to me.

--An Anxious Author in Axminster

Dear Anxious,

The general rule for indefinite articles is to use a before consonants and an before vowels. The trick here is to use your ears (how the acronym is pronounced), not your eyes (how it's spelled).

HIV (pronounced "aitch eye vee") begins with a vowel sound, so an HIV patient is correct. HIPAA (pronounced "hippa") begins with a consonant sound, so a HIPAA form is correct.

H is only one of a handful of consonants in English whose names start with vowel sounds. Here are some more examples of acronyms that might trip you up, depending on whether they are pronounced as words or as a series of letters.

  • a FASB rule; an FOB airfield
  • a LAN schematic; an LAPD memo
  • a MOMA exhibit; an MRI test
  • a NICU nurse; an NPO order
  • a SAM base; an SAT exam

There are also two vowels in English whose names start with consonant sounds. Can you spot them?



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