Definition of doublets:
(n) :
A pair of two similar or equal things; couple.
(n) :
(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). See also Appendix:Glossary#doublet.
(n) :
A man’s close-fitting jacket, with or without sleeves, worn by European men from the 1400s to the 1600s.
(n) :
(printing, US) A word or phrase set a second time by mistake.
(n) :
Either of two dice, each of which, when thrown, has the same number of spots on the face lying uppermost.
(n) :
(lapidary) An imitation gem made of two pieces of glass or crystal with a layer of color between them.