Speech turned between two or more, where each shapes what the other says next. A conversation is built, not delivered.
Latin conversatio (frequent turning-about together, intercourse), from conversari (to keep turning together), from com- (together) + versare (to turn); speech turned between two or more, each one shaping what the other says next.
Latin versare is to turn, and a conversation is literally a turning shared between speakers, never a straight line from one to the other. What either side says next is shaped by the turn just taken, not decided ahead of it.