Definition of underlay

• v. t. - To lay beneath; to put under.
• v. t. - To raise or support by something laid under; as, to underlay a cut, plate, or the like, for printing. See Underlay, n., 2.
• n. - To put a tap on (a shoe).
• v. i. - To incline from the vertical; to hade; -- said of a vein, fault, or lode.
• n. - The inclination of a vein, fault, or lode from the vertical; a hade; -- called also underlie.
• n. - A thickness of paper, pasteboard, or the like, placed under a cut, or stereotype plate, or under type, in the from, to bring it, or any part of it, to the proper height; also, something placed back of a part of the tympan, so as to secure the right impression.