DUPLE

Note: the obsolete adjective definition is a general sense.
in mathematics, it is applied to the proportion of two quantities one of which is double of the other; 
in music, it is applied to ‘time’ or rhythm having two beats in the bar.

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Pronunciation of DUPLE

ETYMOLOGY
Adjective and noun:  from Latin duplus double, from duo two + -plus, from root ple- to fill
Verb:  from Latin duplāre to double, from dupl-us duple

EXAMPLE
From: Miscellaneous Poems By John Byrom: 
To which are added his life and notes by the editor,
Volume I, 1814
A full and true Account of A Horrid and Barbarous Robbery.
Committed in Epping Forest, on the Body of the Cambridge Coach:
In a letter to Martin Folkes, Esq.