phase

US /feɪz/
UK /feɪz/
"phase" picture
1.

a distinct period or stage in a process of change or development

:
The project is currently in its initial phase.
The moon goes through different phases.
1.

to carry out (something) in stages

:
The company plans to phase out the old software over the next year.
They will phase in the new regulations over several months.