Reciprocity
Etymology
From Latin reciprocus "returning the same way, moving back and forth," probably from re- "back" plus pro "forward" — the image of a tide or motion that goes out and comes back. Reciprocity is that back-and-forth made into a social rule.
noun · /res-uh-PROSS-uh-tee/
The practice of exchanging benefits so that giving and receiving stay in balance over time.
What it names
A handle for the invisible ledger that keeps relationships fair — the norm that a gift, favor, or kindness calls for one in return.
Example
The friendship soured once the reciprocity broke down — she was always the one calling, planning, remembering.
Related idea
Distinct from mutuality: reciprocity tracks a sequence of exchanges that should balance out ("you did for me, so I do for you"), while mutuality is a shared state of caring that need not be itemized. Healthy relationships have mutuality; transactional ones live and die by reciprocity.