재미없다
jaemieopda · TOPIK 1
to be boring, uninteresting
재미 (fun) + 없다 (to not exist) = there is no fun
재미 means fun or interest, and 없다 means to not exist or to lack. Together: fun is absent, so it is boring. Its opposite swaps the ending: 재미있다 = fun exists = to be interesting.