Source : Webster's Revised Unabridged Dictionary (1913)

Underlaid \Un`der*laid"\, a.
   Laid or placed underneath; also, having something laid or
   lying underneath.

Source : WordNet®

underlay
     See {underlie}
     [also: {underlaid}]

underlay
     n : a pad placed under a carpet [syn: {carpet pad}, {rug pad}, {underlayment}]
     v 1: raise or support (the level of printing) by inserting a
          piece of paper or cardboard under the type; "underlay
          the plate"
     2: put (something) under or beneath; "They underlaid athe
        shingles with roofing paper"
     3: provide with a base, support, lining, or backing; "underlay
        the boards with joists"
     [also: {underlaid}]

underlaid
     See {underlay}