In my online dictionary, I pull definitions from Vikivortaro, and sometimes from ReVo (when a word is missing from Vikivortaro – such as ‘asymptote’). My online dictionary gives an important extra feature to the Esperanto entries, however, namely that of addressability. That is, using my online dictionary, you can bookmark a specific word.

What about "forproksimiĝanta linio/kurvo/rekto" for bonlingva version of "asymptote"?

NB: Bonlingva ; from what Claude Piron calls "la bona lingvo", using compound words rather than neologisms.