Source : Webster's Revised Unabridged Dictionary (1913)

Interpreter \In*ter"pret*er\, n. [Cf. OF. entrepreteur, L.
   interpretator.]
   One who or that which interprets, explains, or expounds; a
   translator; especially, a person who translates orally
   between two parties.

         We think most men's actions to be the interpreters of
         their thoughts.                          --Locke.

Source : WordNet®

interpreter
     n 1: someone who mediates between speakers of different languages
          [syn: {translator}]
     2: someone who uses art to represent something; "his paintings
        reveal a sensitive interpreter of nature"; "she was famous
        as an interpreter of Shakespearean roles"
     3: an advocate who represents someone else's policy or purpose;
        "the meeting was attended by spokespersons for all the
        major organs of government" [syn: {spokesperson}, {representative},
         {voice}]
     4: (computer science) a program that translates and executes
        source language statements one line at a time [syn: {interpretive
        program}]

Source : Free On-Line Dictionary of Computing

interpreter
     
         A program which executes other programs.  This
        is in contrast to a {compiler} which does not execute its
        input program (the "{source code}") but translates it into
        executable "{machine code}" (also called "{object code}")
        which is output to a file for later execution.  It may be
        possible to execute the same source code either directly by an
        interpreter or by compiling it and then executing the {machine
        code} produced.
     
        It takes longer to run a program under an interpreter than to
        run the compiled code but it can take less time to interpret
        it than the total required to compile and run it.  This is
        especially important when prototyping and testing code when an
        edit-interpret-debug cycle can often be much shorter than an
        edit-compile-run-debug cycle.
     
        Interpreting code is slower than running the compiled code
        because the interpreter must analyse each statement in the
        program each time it is executed and then perform the desired
        action whereas the compiled code just performs the action.
        This run-time analysis is known as "interpretive overhead".
        Access to variables is also slower in an interpreter because
        the mapping of identifiers to storage locations must be done
        repeatedly at run time rather than at compile time.
     
        There are various compromises between the development speed
        when using an interpreter and the execution speed when using a
        compiler.  Some systems (e.g. some {Lisp}s) allow interpreted
        and compiled code to call each other and to share variables.
        This means that once a routine has been tested and debugged
        under the interpreter it can be compiled and thus benefit from
        faster execution while other routines are being developed.
        Many interpreters do not execute the source code as it stands
        but convert it into some more compact internal form.  For
        example, some {BASIC} interpreters replace {keywords} with
        single byte tokens which can be used to {index} into a {jump
        table}.  An interpreter might well use the same {lexical
        analyser} and {parser} as the compiler and then interpret the
        resulting {abstract syntax tree}.
     
        There is thus a spectrum of possibilities between interpreting
        and compiling, depending on the amount of analysis performed
        before the program is executed.  For example {Emacs Lisp} is
        compiled to "{byte-code}" which is a highly compressed and
        optimised representation of the Lisp source but is not machine
        code (and therefore not tied to any particular hardware).
        This "compiled" code is then executed (interpreted) by a {byte
        code interpreter} (itself written in {C}).  The compiled code
        in this case is {machine code} for a {virtual machine} which
        is implemented not in hardware but in the byte-code
        interpreter.
     
        See also {partial evaluation}.
     
        (1995-01-30)