How does the word sound?
"An" is used instead of "a" when the following word starts with a vowel sound. Vowel sounds are the sounds of the letters a, e, i, o, u.
Relationship of something to something else and shows something is "for each" or "for every" something else. Can modify a large number of words.
Examples of how the word is used
|Average wages in the mining industry vary between 15 and 20 dollars an hour|
|Only about 37 minutes an orbit were spent in mapping the surface.|