The term originates from the given name 'Tommy', a diminutive of 'Thomas'. Its use to denote a British soldier is famously traced to the 1794 publication "The British Grenadiers," which included a character named "Tommy Atkins," later used as a sample name on official army paperwork. This institutionalized the name as a generic placeholder, cementing its association with the common soldier. The culinary sense, referring to a type of bread roll, likely derives from the name's common, everyday quality, making it a fitting label for a simple, staple food item.

This is a simplex word derived from a proper name. It does not contain separable morphemes in the modern English spelling.