To lay (something) underneath something else; to put under.
To provide a support for something; to raise or support by something laid under.
to underlay a cut, plate, or the like, for printing
To put a tap on (a shoe).
(of a vein, fault, or lode) To incline from the vertical.
To lie in a position directly beneath.
To lie under or beneath.
A stratum of clay underlies the surface gravel.
To serve as a basis of; form the foundation of.
a doctrine underlying a theory
To be subject to; be liable to answer, as a charge or challenge.
To underlay.
A layer (of earth, etc.) that lies under another; substratum.
A soft floor covering that lies under a carpet.
Anything that is underlaid.
A piece of paper pasted under woodcuts, stereotype plates, etc. in a form, to bring them up to the necessary level for printing.
Lyrics; or more specifically, the way in which lyrics are assigned to musical notes.
The underlay in bar 3 is unclear in Handel's manuscript.