a feature embedded in a JVM which allows to compile for the local platform some parts of the JAVA binary code

produces faster code than an interpreter

(JIT compiler) (n.) A compiler that converts all the bytecode into native machine code just as a JavaTM program is run. This conversion results in runtime speed improvements over code that is interpreted by a Java virtual machine (JVM).

A compiler that converts all of the bytecode into native machine code just as a Java program is run. This results in run-time speed improvements over code that is interpreted by a Java virtual machine.

A compiler that takes Java byte code and converts it to more efficient machine-specific code. This is done at run-time.

A program that turns Java Byte code into processor-specific executable software. Just-in-time (JIT) compilers can help overcome the sluggish performance of a Web browser's virtual machine, which runs byte code one instruction at a time