To turn or fold inwardly.
To fold inward to create a hollow space where none had existed, as with a gastrula forming from a blastula.
To fold up or enclose into a sheath-like or pouch-like structure, either naturally or as part of a surgical procedure.
Having one portion of a hollow organ drawn back within another portion.
sheathed
To dig underneath (something), to make a passage for destructive or military purposes; to sap.
To weaken or work against; to hinder, sabotage.
To erode the base or foundation of something, e.g. by the action of water.