bilateral
correlative
interactional
interactive
inverse
reciprocative
reciprocatory
trilateral
algorismic
algorithmic
aliquot
ally
alter ego
alternate
analogon
analogous
analogue
answering
associate
associated
back-and-forth
beating
brother
cardinal
changeable
circling
close copy
close match
coacting
coactive
coadjutant
coadjuvant
coefficient
coequal
cognate
collaborative
collective
collectivist
collectivistic
collusive
combined
commensal
common
communal
communalist
communalistic
communist
communistic
communitarian
commutable
commutative
commutual
companion
compensatory
complement
complemental
complementary
cross
crossbreeding
crossing
hybridisation
hybridization
hybridizing
interbreeding
opposite
reciprocality
reciprocity
amicable
cordial
disinterested
especial
filial
fraternal
indirect
instinctive
mutual
parental
pecuniary
prior
unspoken
voluntary