Definition of "tritone"

The mini-epic “Seasons in the Abyss,” with its ringing tritone interval at the beginning, its extended solos, its medium tempo, was as close as Slayer got to a groove.

2007 February 17, Ben Ratliff, “For Some Unmellowed Metalheads, Middle Age Is Nothing to Fear”, in New York Times‎

In Photoshop’s Duotone mode you can create monotones, duotones, tritones, and quadtones—grayscale images to which you add one, two, three, or four colors.

1995, Adele Droblas Greenberg, Seth Greenberg, “Converting from One Mode to Another”, in Fundamental Photoshop, 2nd edition, Osborne McGraw-Hill, page 380

When using tritones or quadtones (in which three colours are blended together) all the secondary colours are mixed together.

2003, Duncan Evans, “Duotones and Tritones”, in A Comprehensive Guide to Digital Portrait Photography, AVA Publishing SA, page 115

The two colours need not be black and grey; computer duotones can be created from a greyscale original in any two colours; tritones use three inks and quadtones four.

2010, David Präkel, “Duotone”, in The Visual Dictionary of Photography, AVA Publishing SA, page 97

The first cotume[sic] in which Mrs. Earle appeared was a tritone dress of crepe, with a brown velour cloche and brown calf sling pumps.

1950 October 15, “Local Matrons Smartly Model Clothes Here At Event By Junior League”, in The Greenville News, volume LXXVI, number 288, Greenville, S.C., page two

Fortrel-and-rayon-linen tritone dress, with drawstring waist.

1963 May, “Thirty summer fashions”, in McCall’s, page 186

Tritone jacket has contrast nylon inserts. 80(Blue/Red/Wht.), 38(Beige/Navy/Red).

1979, “Killy Triple Gold Jackets”, in Christmas Wish Book, page 360

It is hard to believe that today’s signs may be tomorrow’s beloved ghosts, but sure as my 1970’s polyester tritone shirt and my plebeian 1964 Volvo are now “classics,” it will likely be so.

2013, Alexandra Horowitz, “Minding Our Qs”, in On Looking: Eleven Walks with Expert Eyes, Scribner, pages 69–70