subdupleadj.

1570 H. Billingsley tr. Euclid Elements Geom. ix. f. 227 The numbers E, HK, L, and M, are vnto FG, as vnitie and the numbers A, B, C, are vnto D (namely, in subduple proportion).

1648 Bp. J. Wilkins Math. Magick i. vii. 47 One of these under Pulleys doth abate halfe of that heavinesse which the weight hath in it self, and cause the power to be in a sub-duple proportion unto it.

1706 W. Jones Synopsis Palmariorum Matheseos 55 The Ratio of 3 to 6 is 3/6 = ½ or subduple.

1728 E. Chambers Cycl. at Subnormal The Subnormal PR is Subduple the Parameter; and, consequently, an invariable Quantity.

1809 W. Nicholson Brit. Encycl. VI. (at cited word) 3 is said to be subduple of 6, as 6 is duple of 3.

1857 J. S. Eaton Treat. Arithm. 163 The half, third, fourth, etc. of a ratio are called the sub-duple, sub-triple, sub-quadruple ratio, etc.

1991 C. B. Boyer & U. C. Merzbach Hist. Math. (ed. 2) xiv. 262 In the same way the theory of proportions included subduple or subtriple or sub-n-tuple proportion, in which quantities vary as the second or third or nth root.