1. the sound you think when you are giving kudos or kisses to someone- when you are pleased with them
2. the sound you think when you are shouting
evil curses at someone- or just being an
evil little genius
3. anything you want it to be, because that is what "muah" is- it can be said (though i only write it- it is not as cool when said) in many different ways and describes many different moods