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Webster 1913 Edition

Sworn brothers

originally, companions in arms who took an oath to share together good and bad fortune; hence, faithful friends.

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Sworn enemies

determined or irreconcilable enemies.

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Sworn friends

close friends.

pp.

of swear. The officers of government are sworn to a faithful discharge of their duty.

Sworn friends, is a phrase equivalent to determined, close or firm friends.

I am sworn brother, sweet,

To grim necessity.

Sworn enemies, are determined or irreconcilable enemies.

sworn ‎(not comparable)

Given under oath

sworn