Definition of "firebird"

A scarlet tanager, Piranga olivacea. (This species is now classified as belonging to the cardinal family: Cardinalidae)  examples

A Baltimore oriole, Icterus galbula.  examples

A vermilion flycatcher, Pyrocephalus rubinus.  examples

(Slavic mythology) A magical and prophetic glowing or burning bird from a faraway land, which is both a blessing and a harbinger of doom to its captor