Is it ensure, insure, or assure?
early 14c., "to swallow too much; to feed to repletion," probably from Old French gloter "to swallow, gulp down," from Latin gluttire "swallow, gulp down," from PIE root *gwele- "to swallow" (cf. Russian glot "draught, gulp"). Related: Glutted; glutting.
1530s, "a gulp," from glut (v.). Meaning "condition of being full or sated" is 1570s; mercantile sense is first recorded 1590s.
An oversupply of goods on the market.