noun

• (Ancient Rome, military, historical) A shelter formed by a body of troops holding their shields or targets close together over their heads.
• A shelter of similar shape for miners, etc.
• (anatomy) The fornix.
• (music) A kind of lyre; so called in allusion to the lyre of Mercury, fabled to have been made of the shell of a tortoise.
• (pathology) An encysted tumour.