A versus An

Many of us have grown with the thumb-rule:

Use the article 'a' before words starting with a consonant and use 'an' before words starting with a 'vowel'.

I had also been following this rule diligently until about 2 years ago. If you have been doing the same, you are in for a surprise. Do you know that this rule has some exceptions? For example,

a. It's fine to say "A man", but it's wrong to say "A honest man" (correct usage is "An honest man").

b. It's fine to say "An umbrella" but it's wrong to say "An used umbrella" (correct usage is 'A used umbrella').

The choice of article (a or an) depends upon the sound (phonetics) of the first letter of the word, rather than whether the first-letter is a vowel or a consonant.

If you follow the second rule, you'll always get it right. Now let's look at some examples to understand what I mean.

a. An honest man: The 'h' in 'honest' is silent. So, it's pronounced 'onest', starting with the sound of an 'o'. Since the original rule says, if the word starts with 'o', use a 'an', therefore, we use 'an' here.

b. A used umbrella: When a 'u' sounds like a 'y' as in 'you', we use 'a' (instead of 'an'). Remember, the original rule says - if the word starts with 'y', use 'a'.

c. A one-day match: When a 'o' sounds like a 'w' as in 'won', we use 'a' (instead of 'an'). Fall back to the original rule - before a word starting with 'w', use 'a'.

The same rule applies to abbreviations and acronyms. Don't go by how the word is written but by how it sounds. Examples:

a. A UNESCO representative: 'U' in 'UNESCO' sounds like 'y' in 'you'. So, we use 'a' instead of 'an'.

b. Koby Bryant is an NBA star. The starting sound of 'N' in 'NBA' sounds like 'a' in 'Antartica', so we use 'an' instead of 'a'.

More examples (with correct usage):

a. Rajan has a Master of Business Administration (MBA) degree. Compare with example (b) below.

b. Rajan has an MBA degree

c. An American car

d. A United States aircraft

e. A U.S. aircraft

f. A horn

g. An honor

h. An hour

i. A union

j. A university

The bottomline is that when it comes to articles 'a' and 'an', use your ears, not your eyes !