adv. 1. In a reciprocal manner; so that each affects the other, and is equally affected by it; interchangeably; mutually. [ 1913 Webster ]
These two particles do reciprocally affect each other with the same force. Bentley. [ 1913 Webster ]
2. (Math.) In the manner of reciprocals. [ 1913 Webster ]
Reciprocally proportional (Arith. & Alg.), proportional, as two variable quantities, so that the one shall have a constant ratio to the reciprocal of the other. [ 1913 Webster ]