Characterized by many bumps or a series of bumps; having a bouncy, jolting quality (informal/childish).
From 'bump' plus informal '-ity' suffix (similar to 'lumpity', 'jumpity'), creating a playful, descriptive adjective.
'Bumpity' is the kind of word children invent and that actually gets adopted into informal speech because it's so perfectly onomatopoetic—it sounds like what it means.
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