early 15c., "cause to swell," from Latin inflatus (source also of Italian enfiare, Spanish inflar, French enfler), past participle of inflare "blow into, puff up," figuratively "inspire, encourage," from in- "into" (from PIE root *en "in") + flare "to blow" (from PIE root *bhle- "to blow"). Economics sense (of prices, currency, etc.) is from 1843. In some senses a back-formation from inflation. Related: Inflated; inflating.