Checkmate means king is in trap and there is no way out.
If it is my turn and opponent's king has a way out from trap, am I said to win the game?
EDIT: Suppose my rook is in the adjacent column w.r.t opponent's king and I move my rook so that it is in the same column with free space by the position of King. Opponent somehow doesn't observe the check and make a move that can't break my check. Now, it's my turn and Let king has all 6 ways out from the check. But after alll it's my turn so is King checkmated or not?