So in #chess, "a turn" and "a move" are the same thing, and refer to *both* players moving a piece each. The numbers in front of written moves are turn numbers; "1. e4 e5" is one turn. Okay.

A single player moving a piece is a ply, or a half-turn, or a half-move. In practice I have never heard anyone say these. People say "your turn" because that is a normal and sensical thing to say. If I told someone it was their ply they would probably look at me weird.

So "a turn" consists of "white's turn" followed by "black's turn".

In practice, this isn't so bad, because context.

But it gets harder when you've constructed a weird extended turn system and you need to describe it for players and phrases like "every n turns" are unclear because that might be "every n turns" or "every n/2 turns" or "every n*2 turns".