re ‧ cip ‧ ro ‧ cal /rɪˈsɪprək ə l/ BrE AmE adjective formal
[ Date: 1500-1600 ; Language: Latin ; Origin: reciprocus 'returning the same way' , from re- 'back' + pro- 'forward' ]
a reciprocal arrangement or relationship is one in which two people or groups do or give the same things to each other ⇨ mutual :
He spoke of the necessity for a reciprocal relationship that would be useful for all sides.
Such treaties provide reciprocal rights and obligations.
—reciprocally /-kli/ adverb