adjective
fraternal
fruh-TUR-nuhl/frəˈtɜːrnl/
Of brothers or the bond between them.
The brothers clasp each other's shoulders in a fraternal embrace.

Etymology
Latin fraternus meant “brotherly” and also “friendly, closely allied.” Fraternal thus applies both to actual brothers and to people whose association is understood as a brotherhood.
In context
Among the grotesque personages sculptured on the wall, there was one to whom he was particularly attached, and with which he often seemed to exchange fraternal glances.
More examples
- Despite their disagreements, a strong fraternal bond holds them together.
- He offers fraternal advice to his younger brother.
- The fraternal society raises money for local families.
Forms
fraternal
fraternally adverb — In a brotherly or mutually supportive way.
fraternity noun — A society organized as a brotherhood.
Similar words
- brotherly
- More common for warm affection or support between brothers.
- familial
- Refers to family relationships generally, not specifically to brothers.