E. Cobham Brewer 1810–1897. Dictionary of Phrase and Fable. 1898.
Ra’ra A’vis (Latin, a rare bird).
A phenomenon; a prodigy; a something quite out of the common course. Black swans are now familiar to us; they are natives of Australia, and have given its name to the “Swan river.” At one time a black swan was emphatically a rara avis.
