n. & v.
n. 1 a distinct period or stage in a process of change or development. 2 each of the aspects of the moon or a planet, according to the amount of its illumination, esp. the new moon, the first quarter, the last quarter, and the full moon. 3 Physics a stage in a periodically recurring sequence, esp. of alternating electric currents or light vibrations. 4 a difficult or unhappy period, esp. in adolescence. 5 a genetic or seasonal variety of an animal's coloration etc. 6 Chem. a distinct and homogeneous form of matter separated by its surface from other forms.
v.tr. carry out (a programme etc.) in phases or stages. in phase having the same phase at the same time. out of phase not in phase. phase in (or out) bring gradually into (or out of) use. phase rule Chem. a rule relating numbers of phases, constituents, and degrees of freedom. three-phase (of an electric generator, motor, etc.) designed to supply or use simultaneously three separate alternating currents of the same voltage, but with phases differing by a third of a period. phasic adj.
[ F phase & f. earlier phasis f. Gk phasis appearance f. phaino phan- show ]