Underlay

verb (used with object), underlaid, underlaying.
1.
to lay under or beneath.
2.
to provide with something laid underneath; raise or support with something laid underneath:
The manufacturer underlays the chrome finish with a zinc coating.
3.
to extend across the bottom of.
noun
4.
something underlaid.
5.
Printing. a piece or pieces of paper put under type or cuts to bring them to the proper height for printing.
verb (used with object), underlay, underlain, underlying.
1.
to lie under or beneath; be situated under.
2.
to be at the basis of; form the foundation of.
3.
Grammar. to function as the root morpheme or original or basic form of (a derived form): The form “boy” underlies “boyish.”.
4.
Finance. to be primary to another right or security.
verb (transitive) (ˌʌndəˈleɪ) -lays, -laying, -laid
1.
to place (something) under or beneath
2.
to support by something laid beneath
3.
to achieve the correct printing pressure all over (a forme block) or to bring (a block) up to type height by adding material, such as paper, to the appropriate areas beneath it
noun (ˈʌndəˌleɪ)
4.
a layer, lining, support, etc, laid underneath something else
5.
(printing) material, such as paper, used to underlay a forme or block
6.
felt, rubber, etc, laid beneath a carpet to increase insulation and resilience
verb (transitive) -lies, -lying, -lay, -lain
1.
to lie or be placed under or beneath
2.
to be the foundation, cause, or basis of: careful planning underlies all our decisions
3.
(finance) to take priority over (another claim, liability, mortgage, etc): a first mortgage underlies a second
4.
to be the root or stem from which (a word) is derived: “happy” underlies “happiest”