FRATERNIZE
fraternize, fraternise
(verb) be on friendly terms with someone, as if with a brother, especially with an enemy
Source: WordNet® 3.1
Etymology
Verb
fraternize (third-person singular simple present fraternizes, present participle fraternizing, simple past and past participle fraternized)
(intransitive) To associate with others in a brotherly or friendly manner.
(intransitive) To associate as friends with an enemy, in violation of duty.
(intransitive) To have an intimate or sexual relationship with a forbidden member of the opposite sex; as, in some cases, football players with cheerleaders.
Source: Wiktionary
Fra"ter*nize ( or ; 277), v. i. [imp. & p. p. Fraternized; p. pr. &
vb. n.. Fraternizing.] Etym: [Cf. F. fraterniser.]
Definition: To associate or hold fellowship as brothers, or as men of like
occupation or character; to have brotherly feelings.
Fra"ter*nize, v. t.
Definition: To bring into fellowship or brotherly sympathy.
Correspondence for fraternizing the two nations. Burke.
Source: Webster’s Unabridged Dictionary 1913 Edition