1. (adj)Carboniferous, Carboniferous period from 345 million to 280 million years ago
2. (adj)carboniferous of or relating to the Carboniferous geologic era Synonyms: carbonic, carbonous, carbonaceous
3. (adj)carbonaceous, carbonous, carbonic, carboniferous relating to or consisting of or yielding carbon Synonyms: carbonic, carboniferous, carbonous, carbonaceous