1. an angle that is not a right angle or a multiple of a right angle;

The Collaborative International Dictionary of English v.0.48:

Oblique \Ob*lique"\, a. [F., fr. L. obliquus; ob (see Ob-) + liquis oblique; cf. licinus bent upward, Gr. le`chrios slanting.] [Written also oblike.] [1913 Webster] 1. Not erect or perpendicular; neither parallel to, nor at right angles from, the base; slanting; inclined. [1913 Webster] It has a direction oblique to that of the former motion. --Cheyne. [1913 Webster] 2. Not straightforward; indirect; obscure; hence, disingenuous; underhand; perverse; sinister. [1913 Webster] The love we bear our friends . . . Hath in it certain oblique ends. --Drayton. [1913 Webster] This mode of oblique research, when a more direct one is denied, we find to be the only one in our power. --De Quincey. [1913 Webster] Then would be closed the restless, oblique eye. That looks for evil, like a treacherous spy. --Wordworth. [1913 Webster] 3. Not direct in descent; not following the line of father and son; collateral. [1913 Webster] His natural affection in a direct line was strong, in an oblique but weak. --Baker. [1913 Webster] Oblique angle, Oblique ascension, etc. See under Angle, Ascension, etc. Oblique arch (Arch.), an arch whose jambs are not at right angles with the face, and whose intrados is in consequence askew. Oblique bridge, a skew bridge. See under Bridge, n. Oblique case (Gram.), any case except the nominative. See Case, n. Oblique circle (Projection), a circle whose plane is oblique to the axis of the primitive plane. Oblique fire (Mil.), a fire the direction of which is not perpendicular to the line fired at. Oblique flank (Fort.), that part of the curtain whence the fire of the opposite bastion may be discovered. --Wilhelm. Oblique leaf. (Bot.) (a) A leaf twisted or inclined from the normal position. (b) A leaf having one half different from the other. Oblique line (Geom.), a line that, meeting or tending to meet another, makes oblique angles with it. Oblique motion (Mus.), a kind of motion or progression in which one part ascends or descends, while the other prolongs or repeats the same tone, as in the accompanying example. Oblique muscle (Anat.), a muscle acting in a direction oblique to the mesial plane of the body, or to the associated muscles; -- applied especially to two muscles of the eyeball. Oblique narration. See Oblique speech. Oblique planes (Dialing), planes which decline from the zenith, or incline toward the horizon. Oblique sailing (Naut.), the movement of a ship when she sails upon some rhumb between the four cardinal points, making an oblique angle with the meridian. Oblique speech (Rhet.), speech which is quoted indirectly, or in a different person from that employed by the original speaker. Oblique sphere (Astron. & Geog.), the celestial or terrestrial sphere when its axis is oblique to the horizon of the place; or as it appears to an observer at any point on the earth except the poles and the equator. Oblique step (Mil.), a step in marching, by which the soldier, while advancing, gradually takes ground to the right or left at an angle of about 25[deg]. It is not now practiced. --Wilhelm. Oblique system of coordinates (Anal. Geom.), a system in which the coordinate axes are oblique to each other. [1913 Webster]The Collaborative International Dictionary of English v.0.48:

Angle \An"gle\ ([a^][ng]"g'l), n. [F. angle, L. angulus angle, corner; akin to uncus hook, Gr. 'agky`los bent, crooked, angular, 'a`gkos a bend or hollow, AS. angel hook, fish-hook, G. angel, and F. anchor.] 1. The inclosed space near the point where two lines meet; a corner; a nook. [1913 Webster] Into the utmost angle of the world. --Spenser. [1913 Webster] To search the tenderest angles of the heart. --Milton. [1913 Webster] 2. (Geom.) (a) The figure made by. two lines which meet. (b) The difference of direction of two lines. In the lines meet, the point of meeting is the vertex of the angle. [1913 Webster] 3. A projecting or sharp corner; an angular fragment. [1913 Webster] Though but an angle reached him of the stone. --Dryden. [1913 Webster] 4. (Astrol.) A name given to four of the twelve astrological "houses." [Obs.] --Chaucer. [1913 Webster] 5. [AS. angel.] A fishhook; tackle for catching fish, consisting of a line, hook, and bait, with or without a rod. [1913 Webster] Give me mine angle: we 'll to the river there. --Shak. [1913 Webster] A fisher next his trembling angle bears. --Pope. [1913 Webster] Acute angle, one less than a right angle, or less than 90[deg]. Adjacent or Contiguous angles, such as have one leg common to both angles. Alternate angles. See Alternate. Angle bar. (a) (Carp.) An upright bar at the angle where two faces of a polygonal or bay window meet. --Knight. (b) (Mach.) Same as Angle iron. Angle bead (Arch.), a bead worked on or fixed to the angle of any architectural work, esp. for protecting an angle of a wall. Angle brace, Angle tie (Carp.), a brace across an interior angle of a wooden frame, forming the hypothenuse and securing the two side pieces together. --Knight. Angle iron (Mach.), a rolled bar or plate of iron having one or more angles, used for forming the corners, or connecting or sustaining the sides of an iron structure to which it is riveted. Angle leaf (Arch.), a detail in the form of a leaf, more or less conventionalized, used to decorate and sometimes to strengthen an angle. Angle meter, an instrument for measuring angles, esp. for ascertaining the dip of strata. Angle shaft (Arch.), an enriched angle bead, often having a capital or base, or both. Curvilineal angle, one formed by two curved lines. External angles, angles formed by the sides of any right-lined figure, when the sides are produced or lengthened. Facial angle. See under Facial. Internal angles, those which are within any right-lined figure. Mixtilineal angle, one formed by a right line with a curved line. Oblique angle, one acute or obtuse, in opposition to a right angle. Obtuse angle, one greater than a right angle, or more than 90[deg]. Optic angle. See under Optic. Rectilineal or Right-lined angle, one formed by two right lines. Right angle, one formed by a right line falling on another perpendicularly, or an angle of 90[deg] (measured by a quarter circle). Solid angle, the figure formed by the meeting of three or more plane angles at one point. Spherical angle, one made by the meeting of two arcs of great circles, which mutually cut one another on the surface of a globe or sphere. Visual angle, the angle formed by two rays of light, or two straight lines drawn from the extreme points of an object to the center of the eye. For Angles of commutation, draught, incidence, reflection, refraction, position, repose, fraction, see Commutation, Draught, Incidence, Reflection, Refraction, etc. [1913 Webster]WordNet (r) 3.0 (2006):

oblique angle n 1: an angle that is not a right angle or a multiple of a right angle [ant: right angle]