X antiX (clockwise anticlockwise) X disX (interest disinterest) X imX (mobile immobile, potent impotent) X inX (consistent inconsistent) X malX (practice malpractice) X misX (fortune misfortune) X nonX (playing nonplaying; aligned nonaligned) X unX (classified unclassified) lX illX (legitimate illegitimate; legal illegal) rX irrX (regular irregular) imX exX (implicit explicit) inX exX (introvert extrovert) upX downX (uphill downhill) overX underX (overcharge undercharge) Xless Xful (harmless harmful)