spelunk

spelunk · noun¹

1. Ancient Greek · derived fromσπῆλυγξ“cave”
2. Latin · derived fromspelunca
3. Old French · derived fromspelonque
4. Middle English · inherited fromspelunke
5. English todayspelunk

From Middle English spelunke, from Old French spelonque and/or Latin spelunca, from Ancient Greek σπῆλυγξ (spêlunx, “cave”), related to σπέος (spéos). Cognates include Middle Dutch spelunke, spelonke, German Spelunke.

spelunk · verb²

U.S., 1940s. Back-formation from spelunker.