I. ən, (ˈ)an indefinite article
Etymology: Middle English, from Old English ān one — more at one
Date: before 12th century
: a II
Usage: see a II
II. ən, an preposition
Date: before 12th century
: a III,2
Usage: see a II
III. conjunction
or an'
Date: 12th century
1. see and : and
2. ˈan archaic : if
IV. abbreviation
Etymology: Latin annum; annus
year