n. Open image in new window Also called luting, a mixture of cement and clay used to seal the joints between pipes, etc. 2. (Medicine / Dentistry) Dentistry a thin layer of cement used to fix a crown or inlay in place on a tooth; vb (Miscellaneous Technologies / Building) (tr) to seal (a joint or surface) with lute [via Old French ultimately from Latin lutum clay]. Generally, a material placed around a conduit for physically securing and/or thermally insulating for a gas or liquid. Some modern polymeric composite lutens have been developed.