An

Part of speech: determiner

Definitions

1. The indefinite article placed before a singular noun that begins with a vowel sound ; an archaic conjunction meaning if, used to introduce a condition
2. A determiner used before a singular countable noun starting with a vowel sound ; an obsolete conjunction equivalent to if, introducing a supposition
3. The indefinite article that precedes words beginning with a vowel sound ; a dated conjunction signifying if, used to set up a possible condition

Etymology: The word "an" is a shortened form of "one," the same number that gives us "one" in every counting sense. Its older form, "ān," was simply the numeral, and over centuries it lost its stress and its vowel weakened, so that in ordinary speech it came to be used before consonants as the indefinite article. The "a" form took over before consonant sounds, while "an" survived before vowels, which is why we still say "an apple" but "a pear." The source also places "an" alongside "on," the preposition, which is the same word in a different role. In Old English "an" could carry the sense of "on" or "in," as in "on" meaning "into a state," a usage that survives in phrases like "an fire." Both forms descend from a single ancestor, so the article and the preposition are, at root, siblings that split apart as the language wore down its unstressed words.

Synonyms: a