burn in

Short definition from Wiktionary

Verb

1. 1
   To eat into, as fire.
2. 2
   To fix and render durable, as colours, by means of intense heat.
3. 3
   To imprint indelibly on the mind.
4. 4
   To exercise electrical components by means of burn-in.

Noun

1. 1
   The process by which components of a system are exercised prior to being placed in service (and sometimes before assembly), forcing certain failures to occur under supervised conditions.
2. 2
   The phase preceding a burn-out in which a worker's productivity and engagement with their work declines.