Imaginary Im*ag"i*na*ry, a. [L. imaginarius: cf. F. imaginaire.] Existing only in imagination or fancy; not real; fancied; visionary; ideal. Wilt thou add to all the griefs I suffer Imaginary ills and fancied tortures? --Addison. Imaginary calculus See under Calculus. Imaginary expression or quantity (Alg.), an algebraic expression which involves the impossible operation of taking the square root of a negative quantity; as, [root]-9, a + b [root]-1. Imaginary points, lines, surfaces, etc. (Geom.), points, lines, surfaces, etc., imagined to exist, although by reason of certain changes of a figure they have in fact ceased to have a real existence. Syn: Ideal; fanciful; chimerical; visionary; fancied; unreal; illusive., Adjusting plane Adjusting plane or surface surface (A["e]ronautics) A small plane or surface, usually capable of adjustment but not of manipulation, for preserving lateral balance in an a["e]roplane or flying machine., Pedal Pe"dal, a. [L. pedalis, fr. pes, pedis, foot. See Foot, and cf. Pew.] 1. Of or pertaining to the foot, or to feet, literally or figuratively; specifically (Zo["o]l.), pertaining to the foot of a mollusk; as, the pedal ganglion. 2. Of or pertaining to a pedal; having pedals. Pedal curve or surface (Geom.), the curve or surface which is the locus of the feet of perpendiculars let fall from a fixed point upon the straight lines tangent to a given curve, or upon the planes tangent to a given surface. Pedal note (Mus.), the note which is held or sustained through an organ point. See Organ point, under Organ. Pedal organ (Mus.), an organ which has pedals or a range of keys moved by the feet; that portion of a full organ which is played with the feet., Surface Sur"face`, n. [F. See Sur-, and Face, and cf. Superficial.] 1. The exterior part of anything that has length and breadth; one of the limits that bound a solid, esp. the upper face; superficies; the outside; as, the surface of the earth; the surface of a diamond; the surface of the body. The bright surface of this ethereous mold. --Milton. 2. Hence, outward or external appearance. Vain and weak understandings, which penetrate no deeper than the surface. --V. Knox. 3. (Geom.) A magnitude that has length and breadth without thickness; superficies; as, a plane surface; a spherical surface. 4. (Fort.) That part of the side which is terminated by the flank prolonged, and the angle of the nearest bastion. --Stocqueler. Caustic surface, Heating surface, etc. See under Caustic, Heating, etc. Surface condensation, Surface condenser. See under Condensation, and Condenser. Surface gauge (Mach.), an instrument consisting of a standard having a flat base and carrying an adjustable pointer, for gauging the evenness of a surface or its height, or for marking a line parallel with a surface. Surface grub (Zo["o]l.), the larva of the great yellow underwing moth (Triph[oe]na pronuba). It is often destructive to the roots of grasses and other plants. Surface plate (Mach.), a plate having an accurately dressed flat surface, used as a standard of flatness by which to test other surfaces. Surface printing, printing from a surface in relief, as from type, in distinction from plate printing, in which the ink is contained in engraved lines., Surface Sur"face, v. t. [imp. & p. p. Surfaced; p. pr. & vb. n. Surfacing.] 1. To give a surface to; especially, to cause to have a smooth or plain surface; to make smooth or plain. 2. To work over the surface or soil of, as ground, in hunting for gold., Cylindric Cy*lin"dric (s?-l?n"dr?k), Cylindrical Cy*lin"dric*al (-dr?-kal), a. [Gr. kylindriko`s, from ky`lindros cylinder: cf. F. cylindrique.] Having the form of a cylinder, or of a section of its convex surface; partaking of the properties of the cylinder. Cylindrical lens, a lens having one, or more than one, cylindrical surface. Cylindric, or Cylindrical, surface (Geom.), a surface described by a straight line that moves according to any law, but so as to be constantly parallel to a given line. Cylindrical vault. (Arch.) See under Vault, n.