> A functional language is a language that supports and encourages programming in a functional style.
Seems rather circular
> Seems rather circular
* recurrent
seems more appropriate in this context :-)
more than circular, it offloads the meaning to another term, which is the functional style. Just read a dictionary, you'll see this happen lots of time, where, for example, the definition of an adjective just references the definition of a related noun and that's it.