aid
aide
aide-de-camp
assistant
coacting
coactive
coadjutor
coadjuvant
coefficient
collaborative
collective
collectivist
collectivistic
collusive
combine
combined
commensal
common
communal
communalist
communalistic
communist
communistic
communitarian
concerted
concordant
concur
concurrent
concurring
conjoin
conniving
cooperant
cooperate
cooperating
cooperative
ecumenic
fellow
harmonious
harmonized
helping
joint
league
lieutenant
mutual
noncompetitive
reciprocal
symbiotic
synergetic
synergic
synergistic