What is phase

phase, the

Phase f. '(Time) segment, changing appearance, state form', in astronomy 'form of illumination, respective light form not itself luminous celestial body', in electrical engineering 'vibration state of current strength or voltage in alternating current, one of the three lines of the three-phase network', Adoption (Phasis, middle of 17th century) from Greek phásis (φάσις) 'appearance, the appearance of the stars, moon phase, the showing, signs', to Greek phá͞inesthai (φαίνεσθαι) 'become visible, seem', initially (up to 18th century) in Greek form, then phase, evidently via the plural phases formed in German (2nd half of 18th century). First related to the changing appearance of the moon and the planets, then (end of the 18th century) generalized ‘appearance, change, change, (time) segment’, probably under the influence of the same. French phase, which also influenced the technical usage mentioned above. Phase with Luther (the children of Israel ... were saved by the lord's passage or phase) does not belong here, but reproduces the text of the Vulgate (Ex. 12, 11) est enim Phase (id est transitus) Domini, based on Hebrew päs̠aḥ , aram.pis̠ḥā 'Passover', actually 'the gentle passing' of the Lord or strangling angel at the houses of the Israelites who, at the command of the Lord, painted their doors with the blood of the slaughtered Paschal lamb and thus made them recognizable (while the children of the Egyptians killed). The celebration of the Jewish Passover is based on this representation.