Recipinity is a nostantif. The verb of the verb is to return the favor; the adjective is reciprocal, and the adverb is reciprocal. Reciprocity and reciprocity are very important; The former can be defined as « shared, felt or shown on both sides » and the latter as « collective. » On the basis of this semantic overlap, some modes of use warn against the use of each of the forms of the two words (reciprocally or reciprocally replicated to each other), because they are superfluous. Each of these words has several meanings, some of which are similar, and others do not. Reciprocity can mean « a reciprocal exchange of privileges » and is often applied to things like professional certification (neighbouring countries can have a reciprocal agreement, so the certification an employee needs is applicable to everyone). Approval may mean « sanction, authorization » or simply refer to « the act or approval process. » Latin reciprocus comes back in turn in the same way.