Of, relating to, or having the form of a corymb; corymbose.
From corymb plus Latin -ous suffix (identical in meaning to -osus but slightly different in origin). This is an alternate form of corymbose, both meaning essentially the same thing.
The existence of both 'corymbose' and 'corymbous' is a quirk of scientific terminology evolving over centuries—different botanists adopted slightly different Latin endings, and rather than standardize, both forms persisted in the literature. This redundancy is why scientific papers sometimes feel repetitive but also why they're resilient to changes.
Complete word intelligence in one call. Free tier — 50 lookups/day.