fra ‧ ter ‧ nal /frəˈtɜːnl $ -ɜːr-/ BrE AmE adjective formal
[ Date: 1400-1500 ; Language: Medieval Latin ; Origin: fraternalis , from Latin frater 'brother' ]
1 . showing a special friendliness to other people because you share interests or ideas with them:
fraternal solidarity amongst union members
fraternal association/organization/society
2 . relating to brothers:
fraternal loyalty
—fraternally adverb