(In Irish mythology) either of two of the royal halls of Conchobar, king of Ulster; frequently with reference to an order of warriors or knights (sometimes in full as "Knights of the Red Branch").
Origin
Early 18th century.
Definition of Red Branch in US English:
Red Branch
noun
(In Irish mythology) either of two of the royal halls of Conchobar, king of Ulster; frequently with reference to an order of warriors or knights (sometimes in full as "Knights of the Red Branch").