If something is nested twice, it's "double nested".
If something is nested three times, it's "triple nested".
If something is nested twelve times, it's ... What? "Dodecly nested?"
Edit: Apparently, according to websters-online-dictionary.com as quoted below, the adverbial form of twelve actually is "twelvely", but that form is virtually never used. Is there one that is used?
- Virtually never used adverbial inflection of the adjective twelve.