SesquiplicateSes*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.