Where does the term “throttle quadrant” come from? The area of many flight decks that contains throttles or thrust levers is often referred to as the “throttle quadrant” or “thrust lever quadrant” even if it’s not one of four parts of the panels.

Where does the term come from?
The term quadrant refers to the panel containing the levers and is derived the circular arc in which the throttles are placed:


  throttle quadrant
  
  The recess in which the throttle is located and moves. ... It derives its name from the circular arc in which the throttle is placed. 


Looks like the term entered aviation from the rudder controls in a ship:


  quadrant
  
  
  A frame fixed to the head of a ship's rudder, to which the steering mechanism is attached.
  
  3.1 A panel with slots through which a lever is moved to orient or otherwise control a mechanism.
  


Here's a rudder quadrant



Rudder quadrant; image from titanic-model.com