Ill-natured describes someone who is consistently grumpy, mean-spirited, or unpleasant in their attitude toward others. An ill-natured person seems to take pleasure in being disagreeable or making cutting remarks. Think of the difference between someone having a bad day and snapping at you once, versus someone who habitually responds to others with irritation and hostility.

You might encounter an ill-natured character in a story who complains constantly, criticizes everyone around them, and seems unable to say anything kind. In real life, an ill-natured neighbor might grumble about children playing too loudly or refuse to return a ball that accidentally lands in their yard, not because it causes real problems but because being disagreeable has become their default way of interacting with the world.

While everyone feels cranky sometimes, an ill-natured person has made surliness and unfriendliness into personality traits. It's the opposite of good-natured, which describes someone with a cheerful, friendly disposition who gives others the benefit of the doubt.