1660s, from Latin stagnatum, stagnatus, past participle of stagnare "to stagnate," from stagnatum "standing water, pond, swamp," perhaps from a PIE root *stag- "to seep drip" (cognates: Greek stazein "to ooze, drip;" see stalactite). Figurative use by 1709. Related: Stagnated; stagnating.