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
Use She offered an apposite quotation.
Use He took the opposite seat.
Avoid She offered an opposite quotation. (If you mean it was apt.)