A pock is a small pit or scar left on the skin after a disease like chickenpox or smallpox has healed. When someone gets chickenpox, the itchy bumps eventually scab over and fall off, sometimes leaving behind tiny permanent dents or marks. These little hollows are pocks.

The word most often appears in pockmark or pockmarked, which describes a surface covered with these small dents. Before smallpox was eradicated in the 1970s through vaccination, many people survived the disease but carried pockmarked faces for the rest of their lives. Today you're more likely to see the word used to describe any surface dotted with small holes or craters: a wall pockmarked by hail, or the moon's surface pockmarked by meteor impacts over billions of years.

While pocks usually refer to marks from disease, the word has expanded to describe any surface marked by similar small indentations, whether from illness, damage, or natural wear.