the word 'thundering' is built upon the ancient root for the sound of a storm. its core, 'thunder', descends from proto-germanic þunraz, which is itself derived from the proto-indo-european root (s)tenh₂-, meaning "to thunder" or "to roar". this root is a widespread onomatopoeic formation, imitating the deep, rumbling sound. the addition of the present participle suffix '-ing' transforms the noun/verb into an adjective, a grammatical process common in old english. thus, the literal meaning "making a thunder-like sound" evolved naturally into a modern figurative sense describing anything of immense force, size, or intensity, metaphorically extending the power of the storm.

Structure: thunder (noun/verb) + ing (adjective-forming suffix) - thunder: from old english þunor, of proto-germanic origin, related to dutch donder and german donner. functions as the core noun/verb root denoting the meteorological phenomenon and its associated sound. - ing: from old english -ende, the present participle ending, used here to form an adjective from a verb, indicating the action or quality of the root.