In a cubic manner; in relation to cubes or cubic properties, though this is a rarely used variant of 'cubically.'
From 'cubic' (Greek 'kubos') plus the adverbial suffix '-ly.' This is an alternative adverbial form to 'cubically,' less commonly used in modern usage.
The existence of both 'cubically' and 'cubicly' shows how English speakers were unsure about the best way to form adverbs from 'cubic'—similar debates happened with words like 'historic' versus 'historical.'
Complete word intelligence in one call. Free tier — 50 lookups/day.