Used attributively (e.g., 'run-in period') to describe a preparatory stage.
Definitions
Relating to a preliminary or preparatory stage that occurs before the main part of a process or study. Participants completed a two-week run-in phase before starting the trial.
Derived from the past participle of the phrasal verb 'run in'; describes something that has been conditioned by initial use.
Definitions
Conditioned by initial use so as to operate smoothly; broken in (of machinery, engines, etc.). The engine is fully run-in after its first thousand miles.