Geometry, those which have the antecedents and consequents of the same ratio in both figures.

Reciprocal Proportion is when, in four numbers, the fourth is less than the second by as much as the third is greater than the first, and vice versa. Great use is made of this reciprocal proportion by Sir Isaac Newton and others, in demonstrating the laws of motion.

Reciprocal Terms, amongst logicians, are those which have the same signification, and consequently are convertible, or may be used for each other.