To lock horns is an idiom which means to argue or fight in a very determined way. It is based on the literal meaning of two fighting animals such as deer whose horns lock together while fighting. Deer, as they fight, invariably lock horns.
1. The BJP and the Samajwadi party locked horns over the recent price hike in petrol.
2. In her new movie she is playing the role of a student who locks horns with her professor.
3. Both the ministers locked horns over the plans for the new road.
4. Deepika Padukon locks horn with Katrina Kaif for number one position.
5. Let's settle this peacefully. I don't want to lock horns with anyone.