(1):

(n.) The casing or covering of a ship's bottom and sides; the materials for such covering; as, copper sheathing.

(2):

(n.) The first covering of boards on the outside wall of a frame house or on a timber roof; also, the material used for covering; ceiling boards in general.

(3):

(p. pr. & a.) Inclosing with a sheath; as, the sheathing leaves of grasses; the sheathing stipules of many polygonaceous plants.

(4):

(n.) That which sheathes.