diagonal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• adjective Joining two nonadjacent vertices of a polygon.
• adjective Joining two vertices of a polyhedron not in the same face.
• adjective Having a slanted or oblique direction.
• adjective Having oblique lines or markings.
• adjective Relating to or being the front left and back right feet or the front right and back left feet of a quadruped.
• noun Mathematics A diagonal line or plane.
• noun Something, such as a row, course, or part, that is arranged obliquely.
• noun A fabric woven with diagonal lines.
• noun A virgule.

from The Century Dictionary.

• In geometry, extending, as a line, from one angle to another not adjacent, within any figure.
• Being in an oblique direction; lying obliquely.
• Marked by oblique lines: as, diagonal cloth.
• .
• A soft material used as a ground for embroidery, generally made very wide, and dyed in plain colors without pattern.
• A material for men's wear, especially for coats and waistcoats.
• noun A straight line drawn from one angle to or through another, not adjacent, in any plane or solid figure.
• noun Any oblique line.
• noun Specifically
• noun In chess, checkers, etc., a line of squares running diagonally across the board. See chess.
• noun Same as diagonal cloth, especially in the United States: a term introduced about 1875.

from the GNU version of the Collaborative International Dictionary of English.

• noun A right line drawn from one angle to another not adjacent, of a figure of four or more sides, and dividing it into two parts.
• noun (Engin.) A member, in a framed structure, running obliquely across a panel.
• noun A diagonal cloth; a kind of cloth having diagonal stripes, ridges, or welts made in the weaving.
• adjective (Geom.) Joining two not adjacent angles of a quadrilateral or multilateral figure; running across from corner to corner; crossing at an angle with one of the sides.
• adjective (Masonry) herringbone work. See Herringbone, a.
• adjective (Shipbuilding) built by forming the outer skin of two layers of planking, making angles of about 45° with the keel, in opposite directions.
• adjective See under Cleavage.
• adjective (Arch.) a chevron or zigzag molding.
• adjective (Arch.) See Cross-springer.
• adjective a scale which consists of a set of parallel lines, with other lines crossing them obliquely, so that their intersections furnish smaller subdivisions of the unit of measure than could be conveniently marked on a plain scale.
• adjective (Geol.) Same as Cross bedding, under Cross, a.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• adjective geometry Joining two nonadjacent vertices (of a polygon or polyhedron).
• adjective Having a slanted or oblique direction, lines or markings.
• adjective Pertaining to the front left and back right (or the front right and back left) legs of a quadruped.
• noun something arranged diagonally or obliquely
• noun a line or cut across a fabric that is not at right angles to a side of the fabric
• noun a punctuation mark used to separate related items of information
• noun geometry a diagonal line or plane
• noun geometry a line joining non-adjacent vertices of a polygon.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun (mathematics) a set of entries in a square matrix running diagonally either from the upper left to lower right entry or running from the upper right to lower left entry
• noun an oblique line of squares of the same color on a checkerboard
• noun a punctuation mark (/) used to separate related items of information
• adjective having an oblique or slanted direction
• noun (geometry) a straight line connecting any two vertices of a polygon that are not adjacent
• adjective connecting two nonadjacent corners of a plane figure or any two corners of a solid that are not in the same face
• noun a line or cut across a fabric that is not at right angles to a side of the fabric