wiktionary
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From puff + -y.
etymonline
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puffy (adj.)
1610s, of wind, "gusty, coming in puffs," from puff + -y (2). Of other things, "swollen," as if with air or some soft substance, by 1660s. The earliest attested use is figurative, "bombastic" (1590s). Related: Puffily; puffiness.
