Use the adjective calloused to describe skin that is thickened and rough from rubbing against something. You might have calloused feet after a summer of walking around barefoot.
Skin can become calloused from repetitive actions — a gardener, for example, might have calloused fingers from pruning rose bushes every day, and runners might get blisters that become calloused heels after rubbing against new shoes. In books, people who do physical work often have hands described as calloused. The Latin root word, callosus, means “thick-skinned.”