doublet

noun

• 1a pair of similar things, in particular two words of the same derivation but having different meanings, for example fashion and faction, cloak and clock.
• (doublets) the same number on two dice thrown at once.
• Physics & Chemistry a pair of associated lines close together in a spectrum or electrophoretic gel.
• a combination of two simple lenses.

• 2a man’s short close-fitting padded jacket, commonly worn from the 14th to the 17th century: they were wearing red velvet doublets and hose