subduple
/ˌsʌbˈdjuːpl/ /ˌsʌbˈdʒuːpl/Mathematics. Now historical
adjective
Designating a proportion or ratio of one to two; that is equal to half of some given quantity.
Origin
Late 16th century; earliest use found in Henry Billingsley (d. 1606), merchant and translator. From post-classical Latin subduplus from classical Latin sub- + duplus.