phasis

[ fey-sis ]

/ ˈfeɪ sɪs /

a manner, stage, or aspect of being; phase.

Words nearby phasis

1650–60; < New Latin < Greek phásis appearance, equivalent to pha- (base of phaínein to show) + -sis -sis

However Xenophon himself seems to have confounded this Phasis with that of Colchis.
The First Four Books of Xenophon's Anabasis|Xenophon
The pheasant gets its name from the river Phasis, in the Eastern country of Pontus.
Stories That Words Tell Us|Elizabeth O'Neill
They further conceive that the apparent Diameters were almost equal; seeing that in the Phasis of 6.
Philosophical Transactions of the Royal Society - Vol 1 - 1666|Various
It is I apparently who am going to cheat you and carry you off to Phasis.
Anabasis|Xenophon

As in the present distich, the Thermodon and Phasis, both prominent in mythology, are mentioned together.
The Last Poems of Ovid|Ovid