roly-poly

The story

The noun is apparently derived from roll (“to turn over and over”) + -y (suffix forming adjectives with the sense ‘having the quality of’), reduplicated with a change of the initial consonant. Compare rolly (“having the ability to roll, rolling”, adjective), which is attested since the 19th century. Noun sense 1.7 (“mischievous or worthless person”) is possibly influenced by poll (“head; (archaic) scalp; (by extension) person”). The adjective and adverb are attested later than the noun, and so are probably derived from it.