What does it mean for a language to be ‘interpreted’?

Question

Do languages like e.g. Ruby (if running MRI, I mean not compiled to byte-code) run actually parsed everytime when an execution of, e.g., method or loop body is needed? I mean, to execute a loop, you need to parse its body N times?

I just always thought that all these programs are being parsed one time at the bootstrap, transformed in a ‘strongly-typed’ statements tree, etc. Is that not true?

Answer 1

I'll just be mean now and say that just about EVERY programming language is interpreted, whether it's a software (Ruby, Python, Java) or a hardware (C, C++) interpreter :)

For a real answer, while I don't know about the internal Ruby implementation, I'm sure as hell they don't parse the statement over and over and over again. While not using bytecode in the original implementation (or did they migrate already?), they use some intermediate representation (you can see it nicely when you want to write C-extensions for it), thus just executing those over and over again.