More clumpy; more lumpy or forming thicker clumps than something else (comparative form of clumpy).
From 'clump' (from Low German 'klump' or Dutch 'klompse') plus the comparative suffix '-ier'. 'Clump' originally meant a heavy mass or block of wood, evolving to mean any gathered mass.
The word 'clumpier' shows how English adjectives bend to our needs—we can add '-ier' to almost any adjective to compare things, creating an infinite gradation from smooth to increasingly lumpy!
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