A prefix is a part of a word that you add at the beginning, before the root word, whereas suffixes are added at the ending. The prefix inter- (as in intermediate), means in; the prefix dis- (as in disengage) means away, apart; the prefix en- (as in enable) means to cause something to happen.
Only the prefix ill- has a negative meaning. For example: illegal (the opposite of legal).
othello trusts iago alot and its ironic because iago is the most decietful peron in the play and when othello finds out at the end of the book he feels like an idiot