disinterested / uninterested
Impartial versus not interested.
Disinterested means having no stake; impartial. Uninterested means not interested. Keep the split. A disinterested judge. An uninterested student. Do not use disinterested for bored.
Examples
Usea disinterested referee
Usean uninterested listener
Avoida disinterested listener (If you mean the listener did not care.)