synallagmatic
‘expressing reciprocal obligations’
Lexical development traced from the Tamil root:
(Latinized form of) Gk. synallagmatikos ‘of or pertaining to a covenant’ < synallagma ‘a covenant, contract’ < syn- ‘together with’ + allagma ‘thing taken in exchange’ < allassein ‘to exchange, barter’ < allos ‘another’ < al < al- < Tamil al