Lock is an English surname derived from the Old English word locc, meaning "lock of hair" or "curl." It likely originated as a nickname for someone with a distinctive tuft or curl of hair. This type of occupational or descriptive surname was common in medieval England, where physical traits, habits, or occupations provided an easy way to distinguish individuals. As a surname, Lock appears in various records across England, particularly in regions where Old English naming traditions were strongest. Its relative simplicity has allowed it to endure over centuries, though it is relatively uncommon today. It is related to the variant Locke, which occasionally appears in American contexts due to immigration and anglicization.