cross, spoil, bilk, scotch, frustrate, baffle, FOIL, queer, cross thwart, forwrought, more...

facilitate, help, assist

crossbar, crosspiece, more...

forward, stern, middle, second, after, centre, same, foremost, rear, wet, next

try to prevent,   ruin plans,   to foil,   put a wrench in,   prevent protection,   defeat the purpose,   to frustrate,   foil, in a way,   prevent completely,   to stop a plan