From Wiktionary, the free dictionary
Learned borrowing from Sanskrit अन- (ana-). Doublet of অ- (o-).
অন- • (ôn-)
- a-, an-, dis-, il-, im-, in-, ir-, -less, mal-, mis-, non-, un-; when prefixed by a word that begins with a vowel
- অনভিজ্ঞ (onbhijno), অনুর্বর (onurbor)