The quality or state of being craggy; the degree to which something is rough and rocky.
From 'craggy' plus the noun-forming suffix '-ness,' which creates abstract nouns describing qualities or conditions. This follows the common English pattern of adjective + -ness.
English has multiple ways to describe the same quality—'rockiness,' 'ruggedness,' and 'cragginess' all work, but each carries slightly different emotional weight, with 'cragginess' sounding more dramatic and literary than the others.
Complete word intelligence in one call. Free tier — 50 lookups/day.