combined effort (noun) cooperation: mutual effort
Detalii: cooperation is always positive, collaboration is positive except in wartime (working with the enemy), and collusion is always negative (working together in secret for a dishonest purpose)
Sinonime: challenge,
deny, disbelieve,
discount,
dispute,
distrust, mistrust, put under suspicion,
reject, scoff at
Antonime: believe, credit,
trust