An Definition

ən; ăn when stressed
article
The form of a used before words beginning with a vowel sound.
An elephant; an hour; an umbrella.
American Heritage
conjuntion
And if; if.
American Heritage
And.
Webster's New World
If.
Webster's New World
abbreviation
Airman, Navy.
American Heritage
In the year.
Webster's New World
Anno (in the year)
American Heritage
Ante (before)
American Heritage

The ccTLD for Netherlands Antilles as assigned by the IANA.

Wiktionary
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suffix
Of, relating to, or resembling.
Brachyuran.
American Heritage
One relating to, belonging to, or resembling.
Librarian.
American Heritage
Unsaturated carbon compound.
Furan.
American Heritage
Anhydride of a carbohydrate.
Dextran.
American Heritage
adjective
One; one sort of.
To bake an apple pie.
Webster's New World
Any one.
Pick an apple from the tree.
Webster's New World
The definition of an is a word used in place of the word “a” when the following word begins with a vowel sound.
An example of when the word an should be used is in front of the word honorary.
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preposition
To each; in each; for each; per.
Two an hour.
Webster's New World
affix
Webster's New World
Webster's New World
(one) Belonging to or having some relation to.
Diocesan.
Webster's New World
(one) Born in or living in.
Mexican.
Webster's New World
(one) Believing in or following.
Lutheran.
Webster's New World
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symbol

(metrology) Symbol for the attonewton, an SI unit of force equal to 10−18 newtons.

Wiktionary
contraction
She'll be ridin' an' comin' up soon. The smart girl an' the silly boy.
Wiktionary

Origin of An

  • Middle English from Old English ān one oi-no- in Indo-European roots

    From American Heritage Dictionary of the English Language, 5th Edition

  • Middle English from Old French from Latin -ānus adj. and n. suff

    From American Heritage Dictionary of the English Language, 5th Edition

  • Middle English short for and and from Old English and

    From American Heritage Dictionary of the English Language, 5th Edition

  • Fr -ain, -en < L -anus, of, belonging to; also directly < L

    From Webster's New World College Dictionary, 5th Edition

  • Alteration of –ane

    From American Heritage Dictionary of the English Language, 5th Edition