1. (of a horse) not responsive to the bit; difficult to control or direct with the reins
Usage: equestrian; often used in horse training and riding contexts
2. (of a person) stubborn, insensitive, or unwilling to listen to advice or criticism
Usage: figurative; informal

Examples

• The hardmouthed mare refused to respond to the rider's gentle pulls on the reins.
• A hardmouthed horse requires experienced handling and patience.
• He was too hardmouthed to accept feedback from his coach.
• The hardmouthed teenager ignored every warning his parents gave him.
• Training a hardmouthed horse takes skill and consistency.
• She had a hardmouthed attitude toward any suggestion of change.