"Ill humor" is a phrase used to describe someone's bad or unpleasant mood. There are a variety of synonyms for this phrase that might be more fitting in different contexts. For example, if someone is grumpy and irritable, you might use the phrase "bad mood" or "cranky." If someone is simply feeling down or unhappy, you might use the term "gloomy" or "melancholy." Other synonyms for "ill humor" might include "morose," "sullen," or "surly." Depending on the context, any one of these words could be a better fit than "ill humor," so it's important to choose the right synonym to convey the right tone.