ruthless
Showing no mercy or kindness to others to get your way.
Ruthless means acting without mercy, pity, or concern for others when pursuing a goal. A ruthless person does whatever it takes to get what they want, even if it means hurting people or being unfair along the way.
Picture a ruthless chess player who sacrifices their own pieces without hesitation to win the game, or a ruthless business owner who fires loyal employees the moment they're no longer useful. Someone acting ruthlessly has set aside their sympathy and kindness.
Ruthless differs from simply being determined or competitive. A determined student works hard to ace every test but helps classmates who struggle. A ruthless student might sabotage others' projects to look better by comparison. The key difference is whether you care about the people affected by your actions.
The word often describes villains in stories: a ruthless pirate captain who shows no mercy, or a ruthless dictator who crushes anyone who disagrees. But it can also describe behavior in everyday situations. A coach who pushes players until they're injured might be called ruthless, as might someone who spreads rumors to win a class election.