Ruthless (adjective)

1. Having or showing no mercy or pity.
2. Unscrupulous and cruel.
3. Having no compassion or consideration for others.

Origin:

Late middle english (in the sense "compassionless"): from ruth, the name of the biblical character who showed great pity and compassion, + -less.

Examples:

1. The ruthless dictator was feared by his people.
2. The ruthless businessman was willing to do anything to succeed.
3. The ruthless criminal showed no remorse for his actions.
4. The ruthless soldier followed orders without question.
5. The ruthless competitor left no room for error.