interpreter

(ĭn-tûrˈprĭ-tər)

1. One who translates orally from one language into another.
2. One who gives or expounds an interpretation: “An actor is an interpreter of other men's words, often a soul which wishes to reveal itself to the world” (Alec Guinness).
3. Computer Science A program that translates an instruction into a machine language and executes it before proceeding to the next instruction.