doublet

A pair of two similar or equal things; couple.

(linguistics) One of two or more different words in a language derived from the same etymological root but having different phonological forms (e.g., toucher and toquer in French or shade and shadow in English).

(literature) In textual criticism, two different narrative accounts of the same actual event.

(lapidary) An imitation gem made of two pieces of glass or crystal with a layer of color between them.

(printing, US) A word or phrase set a second time by mistake.

(quantum mechanics) A quantum state of a system with a spin of ½, such that there are two allowed values of the spin component, −½ and +½.

(computing) A word (or rather, a halfword) consisting of two bytes.

(botany) A very small flowering plant, Dimeresia howellii.

A word ladder puzzle.

An arrangement of two lenses for a microscope, designed to correct spherical aberration and chromatic dispersion, thus rendering the image of an object more clear and distinct.

Either of two dice, each of which, when thrown, has the same number of spots on the face lying uppermost.

(uncountable, obsolete) A game somewhat like backgammon.

(radio) Dipole antenna.

(historical) A man's waistcoat.