un-; non-
bad ...; poor ...
「無」 has another reading with different meanings.
nothing; naught; nought; nil; zero
努力が無駄になることはない。
Effort is never wasted.
無関心ではいられない問題だ。
It's a problem I can't be indifferent to.
無意味なことはやめましょう。
Let's stop doing meaningless things.