tunnel Synonyms

burrow tube passage duct subway conduit underpass underground passage canal passageway bore thill tideway scoop tunneling tunnelling undermine viaduct sett sewer subterraneous subterranean shaft shovel spade sink warren whetstone dig out slit trench bore through gouge out escape route scoop out borehole pipeline stave in cut through mineshaft hollow out crawlway sap adit coupure crosscut delve den digging dig ditch