o‧ver‧drive /ˈəʊvədraɪv $ ˈoʊvər-/ noun [uncountable]

1. an additional gear which allows a car to go fast while its engine produces the least power necessary

2. go into overdrive/be in overdrive to start being very active or working very hard:
Her career has gone into overdrive.

[TahlilGaran] Dictionary of Contemporary English ▲