Late Middle English; earliest use found in The Wycliffite Bible (early version). Apparently either from poor + -ish, or shortened from Middle French appovriss-, extended stem of appovrir to make poor, to become poor, or shortened from Middle French empovriss-, extended stem of empovrir, or from Middle French pouveriss-, extended stem of pouverir; compare -ish. In later use perhaps shortened from impoverish.