Of, relating to, or resembling hazelnuts or the hazelnut tree; nutty in nature or appearance.
From Latin 'avellanea' (hazelnut-related) and English '-ous' suffix. Derived from Latin 'avellana' (hazelnut), which came from the tree's association with a place called Avella in ancient Italy.
The Romans actually named hazel trees after the town of Avella near Naples where they grew abundantly—so your 'avellaneous' cereal connects you linguistically all the way back to ancient Italian geography!
Complete word intelligence in one call. Free tier — 50 lookups/day.