Underlay
WordNet
noun
(1) A pad placed under a carpet
verb
(2) Provide with a base, support, lining, or backing
"Underlay the boards with joists"
(3) Put (something) under or beneath
"They underlaid the shingles with roofing paper"
(4) Raise or support (the level of printing) by inserting a piece of paper or cardboard under the type
"Underlay the plate"