The Collaborative International Dictionary of English v.0.48:

Overdrive \O`ver*drive"\, v. t. & i.
   To drive too hard, or far, or beyond strength.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

overdrive \o"ver*drive`\, n.
   1. (Machinery) A gearing device which causes the drive shaft
      of an automobile or other machine to rotate at a speed
      greater than that of the engine crankshaft.
      [PJC]

   2. (Automotive) The gear setting of a motor vehicle at which
      the overdrive[1] is operative; as, cruising at 80 mph in
      overdrive.
      [PJC]

   3. Hence: [fig.] A state of unusually intense activity; as,
      when they got their new supercomputer, their research
      kicked into overdrive; one look at her made his heart jump
      into overdrive; -- used mostly of the activities of
      persons or groups.
      [PJC]

WordNet (r) 3.0 (2006):

overdrive
    n 1: the state of high or excessive activity or productivity or
         concentration; "Troops are ready to go into overdrive as
         soon as the signal is given"; "Melissa's brain was in
         overdrive"
    2: a high gear used at high speeds to maintain the driving speed
       with less output power
    v 1: drive or work too hard; "The teacher is overworking his
         students"; "Overdriving people often suffer stress"
    2: make use of too often or too extensively [syn: overuse,
       overdrive]

The Free On-line Dictionary of Computing (19 January 2023):

Overdrive

    An Intel Pentium processor which fits into a
   socket designed to accomodate an Intel 486, or into a
   special upgrade socket on the motherboard.

   (1995-03-27)