Interpreter

noun

1. One who conveys what a user of one language is saying or signing, in real time or shortly after that person has finished communicating, to a user of a different language. (Contrasted with a translator.)

   "A Japanese man who is tried before a German court is assisted by an interpreter in making oral statements."

2. One who explains something, such as an art exhibit. One who does heritage interpretation.
3. A program that executes another program written in a high-level language by reading the instructions in real time rather than by compiling it in advance.

   "Programs written in the BASIC language are usually run through an interpreter, though some can be compiled."