ADJ. bitter, dangerous, deadly, formidable, implacable, terrible He knew that Carlton could be an implacable foe. | common | old playing in the final against their old foes Italy
VERB + FOE vanquish (figurative) She had fought many battles, vanquished many foes.
PREP. against a ~ to join forces against a common foe
PHRASES friend and foe His newspaper articles criticized friend and foe alike. | friend or foe She was unsure as yet whether he was friend or foe.