ypsilon yp·si·lon (ŭp'sə-lŏn', yōōp'-)
Variant of upsilon.
ypsilon's big Greek letter, outlined in perpetual snow, is one of the famous landmarks of the northern end.
This species is the ypsilon of Borkhausen, and the upsilon of other authors.
This accounts for the presence of v, originating in the Greek ypsilon.
One of the commonest species is the cosmopolitan greasy-cut-worm (Agrotis ypsilon).