the core of the word, 'thud', is onomatopoeic, emerging in middle english to imitate the sound of a heavy blow or fall. it belongs to a class of words where the form directly echoes the sensory experience it describes. the addition of the suffix '-ing', with its old english origins, transforms this sound into an adjective describing something that produces that noise, or a noun for the action or sound itself. thus, 'thudding' elegantly captures the continuous or characteristic occurrence of that specific, dull, impactful sound.

the word 'thudding' is formed from the base 'thud' and the suffix '-ing'. 'thud' is considered a simplex, likely of imitative origin, representing the sound itself. the suffix '-ing' is from old english '-ende', '-inge', forming present participles and verbal nouns.