What's the property of a language called which makes you able to write eg. a bootloader?

Question

What's the name for a property of a programming language (or of its compiler) which makes one able to write independently of any Operating System and any standard|runtime library?

For example, one can write a boot loader in C or in assembly for a given processor platform. How is this property[|ies] described or named?

Example question: "Is Java a <term-here> language, so that I can write a bootloader in it?"