1. A layer of hard subsoil or clay that is difficult to dig through or penetrate.
Usage: geology/soil science term; commonly used in construction and agriculture
2. A firm or uncompromising foundation or basis; bedrock.
Usage: figurative use

Examples

• The construction crew hit hardpan while digging the foundation and had to use special equipment.
• Farmers in the region struggle with hardpan that prevents water from draining properly.
• The hardpan of the organization's values has remained unchanged for decades.
• Roots cannot easily penetrate the hardpan layer in this soil.
• The company's hardpan commitment to quality is evident in every product.