Meaning of DIAGONAL in English


I. (ˈ)dī|agən ə l, -aig-, -g( ə )n ə l, -gnəl adjective

Etymology: Latin diagonalis, from Greek diagōnios from angle to angle (from dia- + -gōnios, from gōnia angle) + Latin -alis -al; akin to Greek gony knee — more at knee


a. : joining two nonadjacent vertices of a rectilinear or polyhedral figure : running across from corner to corner

b. : passing through two nonadjacent edges of a polyhedron

a diagonal plane


a. : inclined obliquely from a reference line (as the vertical or an axis)

wood with a diagonal grain

a map with a number of diagonal lines

a diagonal white cross on a blue ground

b. : having diagonal markings or parts

a diagonal weave

3. crystallog

a. : having reference to certain axes of the isometric system which are the intersections between the principal and the secondary planes of symmetry

b. : having reference to the directions bisecting the angles between lateral axes in the tetragonal and hexagonal systems

• di·ag·o·nal·ly -gən ə l]ē, -gnəl], ]i\ adverb

II. noun

( -s )

1. : a straight line joining any two nonadjacent vertices of a polygon or any two vertices of a polyhedron not in the same face


a. : a diagonal direction : a diagonal row, arrangement, or pattern

water bugs skated hither and thither in apparently purposeless diagonals — S.E.White

neckties with colorful diagonals

b. : a twill weave : a twilled fabric especially of wool

c. : a line of squares running obliquely across a chessboard or checkerboard

one bishop moves along white diagonals

d. : something lying in a diagonal position (as in an inclined plane)

its gable wall rises from the falling diagonal of the ground — American Guide Series: Maryland

3. : the secondary mirror in a Newtonian reflecting telescope that is used to bring the focus to the side of the tube and is usually a flat mirror but sometimes a totally reflecting 45 degrees prism

4. : the symbol / used especially to denote “or” (as in and/or ), “and or” (as in straggler/deserter form ), “per” (as in feet/second ), “in” or “of” (as in U.S. Embassy/Paris ), “shilling” (as in 6/8 d ), or “for” (as in 2/39) to indicate division (as in birth/death ratio ) or the end of a line of verse or of a display line when quoted in running text, to separate terms of quantity (as in 5 tons /7 cwts /57 lbs ) or the figures of a date (as in 1/9/56), or to enclose phonemic rather than phonetic symbols — called also oblique, scratch comma, separatrix, slant, slash, slash mark, solidus, virgule

5. : an inclined member of a truss or bracing system excepting the end post of a truss and the top chord of a roof truss whose top chords are inclined

Webster's New International English Dictionary.      Новый международный словарь английского языка Webster.