(umbmäärane artikkel, jääb enamasti tõlkimata) üks, mingi, mingisugune

an(indef. article)

one

There is a boy in the garden.

keegi, kõik

an(indef. article)

any; every

An owl can see in the dark.

iga

an(indef. article)

for each; per

We earn $6 an hour.