Igr

used as an insult towards others meaning not smart. could also mean an unpleasant/unwanted being.

1. stop acting like an Igr and tell me what two plus two is
2. you are being such an Igr, I am going to have to ask you to leave

Un

un is a prefix meaning not. the prefix un is more towards the negative side of root words.

1. You are very UNfortunate
2. You are very UNtidy
3. You are very UNwanted