verb
fraternize
FRAT-er-nyze/ˈfrætərnaɪz/
To associate socially, especially with people considered off-limits.
Employees fraternize with opposing team members over coffee despite their supervisor's disapproval.

Etymology
To fraternize was originally to sympathize as brothers. Its use for cultivating friendship with enemy troops helps explain the modern suggestion of being friendly with people one is expected to avoid.
In context
it also evokes the punishment meted out by the IRA the 1970s to Irish women in their own tribe who fraternize with British soldiers
More examples
- The soldiers are forbidden to fraternize with enemy troops.
- She enjoys fraternizing with other musicians after rehearsals.
- Company rules discourage managers from fraternizing with employees they supervise.
Forms
fraternize · fraternizes · fraternized · fraternizing
fraternization noun — Social contact, especially with forbidden companions.