a sign, stamp, or mark impressed, as by a seal.-especially, the name of any person, written with his own hand, employed to signify that the writing which precedes accords with his wishes or intentions; a sign manual; an autograph.-an outward mark by which internal characteristics were supposed to be indicated.-a resemblance between the external characters of a disease and those of some physical agent, for instance, that existing between the red skin of scarlet fever and a red cloth; -- supposed to indicate this agent in the treatment of the disease.-the designation of the key (when not c major, or its relative, a minor) by means of one or more sharps or flats at the beginning of the staff, immediately after the clef, affecting all notes of the same letter throughout the piece or movement. each minor key has the same signature as its relative major.-a letter or figure placed at the bottom of the first page of each sheet of a book or pamphlet, as a direction to the binder in arranging and folding the sheets.-the printed sheet so marked, or the form from which it is printed; as, to reprint one or more signatures.-that part of a prescription which contains the directions to the patient. it is usually prefaced by s or sig. (an abbreviation for the latin signa, imperative of signare to sign or mark).-to mark with, or as with, a signature or signatures.