flank on

flank (up)on (someone or something)

To be positioned next to someone or something. Two guards flanked on each side of the entrance.
See also: flank

flank (up)on someone or something

to be at the side of someone or something. (Upon is formal and less commonly used than on.) The Victorian mansion flanked on the tall, modern apartment building. It flanked on a broad expanse of fir trees.
See also: flank, on