'Phase in' definitions:

Definition of 'phase in'

From: WordNet
verb
Introduce gradually [ant: phase out]

Definition of 'Phase in'

From: GCIDE
  • Phase in \Phase" in`\ (f[=a]z" [i^]n`), v. t. To begin an activity or to incorporate new elements or replace older elements of an activity in steps, or by degrees. [PJC]