Middle English: from Old French fesan, via Latin from Greek phasianos '(bird) of Phasis', the name of a river in the Caucasus, from which the bird is said to have spread westwards.

• An old name for the river Rion in Georgia in southeast Europe was the Phasis. The Greeks believed that the pheasant originated in that region before it spread westwards, and called it the ‘bird of Phasis’. The region the Phasis flowed through was called Colchis by the Greeks, which was also said to be the land of the Golden Fleece. The modern Latin name for the common pheasant is still Phasianus colchicus ‘the pheasant of Colchis’. The variety of autumn-flowering crocus called a colchicum, gets its name from the same place. It was said by ancient authors to be particularly common there, and the poison that comes from it is said to have been used by the legendary Colchican witch Medea, who helped Jason win the Golden Fleece.