interaction (n.)

• alternation
• answer
• coaction
• commerce
• communication
• communion
• concurrence
• congress
• connection
• contact
• conversation
• converse
• cooperation
• correspondence
• dealing
• dealings
• engagement
• exchange
• information
• interchange
• intercommunication
• intercommunion
• intercourse
• interplay
• mesh
• meshing
• message
• reply
• response
• seesaw
• speaking
• speech
• talking
• telepathy
• touch
• traffic
• truck