phaseyoudaoicibaDictYouDict[phase 词源字典]
phase: [19] Greek phásis (a derivative of the verb phaínein ‘show’, source of English phantom) meant ‘appearance’, and also ‘cyclical apparent form of a planet, moon, etc’. This was adopted into modern Latin as phasis, and it originally passed into English (in the 17th century) in the Latin plural form phases. Phase represents a new singular formed from this. The more familiar modern sense ‘stage in a sequence’ is a metaphorical extension of the astronomical meaning.
=> phantom[phase etymology, phase origin, 英语词源]
phase (n.)youdaoicibaDictYouDict
1705, "phase of the moon," back-formed as a singular from Modern Latin phases, plural of phasis, from Greek phasis "appearance" (of a star), "phase" (of the moon), from stem of phainein "to show, to make appear" (see phantasm). Latin singular phasis was used in English from 1660. Non-lunar application is first attested 1841. Meaning "temporary difficult period" (especially of adolescents) is attested from 1913.
phase (v.)youdaoicibaDictYouDict
"to synchronize," 1895, from phase (n.). Meaning "to carry out gradually" is from 1949, hence phase in "introduce gradually" (1954), phase out (1954). Related: Phased; phasing.