The word 'thumper' is a straightforward agent noun formation from the verb 'thump,' which itself is an onomatopoeic creation from the late 16th century, imitating the sound of a heavy, dull blow. The '-er' suffix, with ancient Germanic origins, is a highly productive agentive marker, as seen in words like 'writer' or 'baker.' Therefore, the literal construction "one who/that which thumps" logically gives rise to its core meaning. Over time, this literal sense was extended informally to describe anything notably large or impressive, evoking the idea of something that makes a significant impact, much like a heavy thump.

Structure: thump (to strike heavily) + er (agent suffix) - thump: Of imitative origin (echoic of a dull, heavy sound). Functional role: The core verb root denoting the action. - er: From Old English -ere, agent-noun suffix. Functional role: Derivational suffix forming a noun meaning "a person or thing that performs the action of the verb."