Epiphany: ἐπιφάνεια

Epiphany (Koine Greek: ἐπιφάνεια, epiphaneia, “manifestation”, “striking appearance”) or Theophany (Ancient Greek (ἡ) Θεοφάνεια, Τheophaneia meaning “vision of God”), which traditionally falls on January 6 (19), the feast which celebrates the revelation of the Most Holy Trinity to the world through the Baptism of the Lord (Mt.3:13-17; Mark 1:9-11; Luke 3:21-22).

“When Thou, O Lord, wast baptized in the Jordan the worship of the Trinity was made manifest! For the voice of the Father bare witness to Thee, calling Thee his Beloved Son. And the Spirit, in the form of a dove, confirmed the truthfulness of his Word. O Christ our
God, who hast revealed Thyself and hast enlightened the world, glory to Thee (Troparion).

Today Thou hast appeared to the universe, end Thy Light, O Lord, has shone on us, who with understanding praise Thee: Thou hast come and revealed Thyself, O Light Unapproachable! (Kontakion).”

See http://www.goarch.org/ourfaith/ourfaith8383/
http://oca.org/orthodoxy/the-orthodox-faith/worship/the-church-year/epiphany
http://orthodoxwiki.org/Theophany