interpreter

A program which executes a translated version of a source program by implementing a virtual machine. Interpreters typically simulate the actions of an idealized Central Processing Unit. An interpreter for Java must implement the Java Virtual Machine (JVM) and executes the bytecodes produced by a Java compiler. The advantage of using an interpreter for Java is that it make the language more portable than if it were a fully compiled language. The bytecode version of a program produced by a Java compiler may be run on any interpreter implementing the JVM.

A module that alternately decodes and executes every statement in some body of code. The Java interpreter decodes and executes bytecode for the Java virtual machine . See also compiler, runtime system.

Strictly speaking, a program that reads a second program and does what the second program says directly without turning the program into a different form first, which is what compilers do. Perl is not an interpreter by this definition, because it contains a kind of compiler that takes a program and turns it into a more executable form (syntax trees) within the perl process itself, which the Perl "run time" system then interprets.