An Old Language With a Growing Digital Fan Club
A nice article on Ozy.com about the Duolingo Esperanto community. Hey wait, that's us! :)
I'm sure "old" was used because Esperanto is older than any human currently alive. Contrast this with other popular conlangs (constructed languages) like Klingon (and maybe even J. R. R. Tolkien's Elvish), which are quite a bit younger (as most conlangs tend to be these days).
Well, yes, old is a relative term, so you are correct. But it does not say an 'old' conlang, it says an old language, comparing it with all languages, which suggests that the author believes it should be counted equal to all languages or her English is a bit flakey and does not understand the use of 'old'.
Fantomius said it pretty good. Just like in English the context of what's being spoken about is taken into account. It's a constructed language of whom all the original speakers (From Zamenhoffs day) are all dead and it has been passed down to a new generation. All about context.