Cruel is an adjective that means willfully causing pain or suffering to others, or feeling no concern about it.
Synonyms include: brutal, vicious, savage, ruthless, heartless.
The term "cruel" can also be used in these contexts:
1. Cruel joke - a joke that is unkind or causes distress
2. Cruel fate - an unfortunate and unavoidable situation
3. Cruel summer - an extremely hot and uncomfortable summer