The process of stregthening or stabilizing by use of an inner layer, usually using paper or fabric. In conservation and other contexts, the process of reinforcing a work by applying a paper or fabric lining with an adhesive, sewing, or another method; examples include lining applied to the support of a paper or canvas support of a work of art, or the lining applied to a garment as an inner layer of cloth.

Source: AAT 

http://vocab.getty.edu/page/aat/300162124