A soldier is one who fights as part of an organized land-based armed force; if that force is for hire the person is generally termed a mercenary soldier, or mercenary. The majority of cognates of the word "soldier" that exist in other languages have a meaning that embraces both commissioned and non-commissioned officers in national land forces.
The word soldier entered modern English in the 14th century from the equivalent Middle English word soudeour, from Anglo-French soudeer or soudeour, meaning mercenary, from soudee, meaning shilling's worth or wage, from sou or soud, shilling. The word is also related to the Medieval Latin soldarius, meaning soldier (literally, "one having pay"). These words ultimately derive the Late Latin word solidus, referring to an Ancient Roman coin used in the Byzantine Empire.