We pre-negotiated several key terms before the official meeting.

pre-negotiated 是动词 pre-negotiate 的过去式形式。pre-negotiate 由前缀 pre-（表示“在...之前”）和动词 negotiate（谈判、协商）组成，意思是“预先谈判、事先商定”。pre-negotiated 表示“已经预先商定好的”。