The word "fraternize" is correct and usable in written English.
You can use it to refer to a situation in which two or more people become friendly and spend time together, such as friendly conversations or socializing. For example: "The two members of the opposing teams fraternized after the game."
They could do business with each other in the marketplace, but they could not fraternize in each other's homes.
Mantegna's friendly relations with several humanists, antiquarians, and university professors are a matter of record, and hence he may be seen as one of the earliest Renaissance artists to fraternize from a position of intellectual equality with such men.
On July 29 some army units began to fraternize with the insurgents.
Crosby and Subban "fraternize a little bit," Subban said.
He does not like lateness: he positions himself outside the rehearsal hall at ten each morning in case the cast wants to fraternize, and rehearsals begin promptly at ten-thirty; lunch is at twelve-forty-five; work finishes at three-thirty.
Little by little activists begin to fraternize with professors and show some interest in attending lectures again.
The boys fraternized with the crowd at Arnold's Malt Shop, where they sipped floats, dumped dimes into the jukebox, fretted about girls, and lamented the minor misunderstandings they had with their parents.
With the help of his son, Telemachus, Odysseus destroys the insistent suitors of his faithful wife, Penelope, and several of her maids who had fraternized with the suitors and reestablishes himself in his kingdom.
Fraternizing with peasants and artisans in the hinterland, these forces helped raise revolutionary enthusiasm but ultimately left such village sansculottes vulnerable to the wrath of the wealthy citizens whom they harassed.
Writer toured it in the company of its chief creator, Dr. Colin M. Turnbull, the Associate Curator of African Ethnology, who on 5 trips spent about 6 years observing & fraternizing with the natives in Kenya, Uganda, Burundi, the Congo & the Sudan.
Of all the charges being levelled, the social one — that the Prime Minister was fraternizing with the wrong sort — is at once the most splenetic and the weakest, especially to anyone familiar with the dance that politicians and newspapers have led one another in the past hundred years.
