# Grammar question regarding acronyms **URL:** \ **Category:** Factual Questions\ **Created:** [March 30, 2004, 3:35pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317 "2004-03-30T15:35:19Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![audiobottle](https://avatars.discourse-cdn.com/v4/letter/a/bc8723/32.png) [@audiobottle](https://boards.straightdope.com/u/audiobottle)\ **Post date:** [March 30, 2004, 3:35pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317/1 "2004-03-30T15:35:19Z")
Here’s something I’ve wondered about for a while now. Say you’re writing a sentence with an acronym in it. Say that acronym spells a word, like HALO (High Altitude Low Opening). Since HALO, when pronounced halo, starts with a consonant, do you put a single “a” in front? Or do you put an “an” in front because when you say H-A-L-O it has a vowel sound in the front? Which is correct? 1. I’m going to do a HALO jump! (pronounced halo) 2. I’m going to do an HALO jump! (pronounced H,A,L,O) This might not be a good example since HALO might be commonly referred to as halo, but you can imagine having a new, less commonly used acronym that could be put in instead. ---
**Author:** ![Acsenray](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/acsenray/32/4519_2.png) [@Acsenray](https://boards.straightdope.com/u/Acsenray)\ **Post date:** [March 30, 2004, 3:44pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317/2 "2004-03-30T15:44:20Z")
The key is _sounds_, not letters. If “HALO” starts with a vowel _sound_ then use “an.” If it starts with a consonant _sound_ then use “a.” Thus, both of your examples are correct. It all depends on how you are pronouncing “HALO.” ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [March 30, 2004, 3:44pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317/3 "2004-03-30T15:44:26Z")
[From this website: > [@](#): > > Use an in place of a when it precedes a vowel sound, not just a vowel. That means it’s “an honor” (the h is silent), but “a UFO” (because it’s pronounced yoo eff oh). This confuses people most often with acronyms and other abbreviations: some people think it’s wrong to use “an” in front of an abbreviation (like “MRI”) because “an” can only go before vowels. Poppycock: the sound is what matters. It’s “an MRI,” assuming you pronounce it “em ar eye.” This jibes with my intuition and [url=http://ccc.commnet.edu/grammar/abbreviations.htm#acronyms]with this website]([http://andromeda.rutgers.edu/~jlynch/Writing/a.html#a](http://andromeda.rutgers.edu/~jlynch/Writing/a.html#a)). Daniel ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [March 30, 2004, 3:46pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317/4 "2004-03-30T15:46:07Z")
Worst. Coding. EVAR! [From this website:](http://andromeda.rutgers.edu/~jlynch/Writing/a.html#a) > [@](#): > > Use an in place of a when it precedes a vowel sound, not just a vowel. That means it’s “an honor” (the h is silent), but “a UFO” (because it’s pronounced yoo eff oh). This confuses people most often with acronyms and other abbreviations: some people think it’s wrong to use “an” in front of an abbreviation (like “MRI”) because “an” can only go before vowels. Poppycock: the sound is what matters. It’s “an MRI,” assuming you pronounce it “em ar eye.” This jibes with my intuition and [with this website](http://ccc.commnet.edu/grammar/abbreviations.htm#acronyms). Daniel ---
**Author:** ![audiobottle](https://avatars.discourse-cdn.com/v4/letter/a/bc8723/32.png) [@audiobottle](https://boards.straightdope.com/u/audiobottle)\ **Post date:** [March 30, 2004, 4:14pm UTC](https://boards.straightdope.com/t/grammar-question-regarding-acronyms/237317/5 "2004-03-30T16:14:19Z")
Ah, thanks. I figured that the sound was probably it, but it’s always good to know for sure.