the word "thunderous" is a transparent english formation, combining the native english noun "thunder" with the productive adjective-forming suffix "-ous", which entered english via old french from latin. the old english þunor itself descends from proto-germanic þunraz, which is thought to be onomatopoeic, imitating the deep, rumbling sound. the suffix "-ous", meaning "full of" or "characterized by," directly attaches this sonic quality to nouns, creating a modern adjective that vividly describes anything possessing the overwhelming power and volume of a thunderclap, whether a literal sound or a metaphorical expression of anger.

Structure: thunder (loud noise) + ous (adjective suffix) thunder (from old english þunor, meaning a loud rumbling or crashing noise heard after a lightning flash); ous (a suffix forming adjectives from nouns, from latin -osus, meaning full of, characterized by)