Proper noun
Hemera
(Greek mythology) The personification and elemental goddess of the day. Her husband is Aether.
And Nyx "from union in love" with Erebus produced Aether (Light) and Hemera (Day). Source: Internet
It should be noted that at the time when John the author of Revelation wrote the verse Revelation 1:10 Sunday was called in both the Greek and the Roman calendars the "Day of The Sun" or "Hemera Heli(o)u in the Greek and "Dies Solis" in the Latin. Source: Internet