apposite / opposite
Apt and on point versus facing or contrary.
Apposite means apt, fitting, exactly to the point: an apposite example. Opposite means facing, contrary, or reverse: the opposite wall, the opposite view. Do not use apposite when you mean “facing,” or opposite when you mean “apt.”
Examples
UseShe offered an apposite quotation.
UseHe took the opposite seat.
AvoidShe offered an opposite quotation. (If you mean it was apt.)