The Collaborative International Dictionary
Sesquiplicate
Sesquiplicate \Ses*quip"li*cate\, a. [Sesqui- + plicate.] (Math.) Subduplicate of the triplicate; -- a term applied to ratios; thus, a and a' are in the sesquiplicate ratio of b and b', when a is to a' as the square root of the cube of b is to the square root of the cube of b', or a:a'::[root]b^ 3:[root]b'^ 3.
The periodic times of the planets are in the
sesquiplicate ratio of their mean distances.
--Sir I.
Newton.
Wiktionary
sesquiplicate
a. Magnified by one and one-half; in a ratio of three to two.