The word quadrant can mean:

• A region of the Cartesian coordinate plane with a specific sign for the x and y coordinates: (+, +), (-, +), (-, -) or (-, +). It is the 2-dimensional case of an Orthant
• (based on the above) One of the four divisions of the city layout of Washington, D.C.
• Another name for sextant

Also see the Wiktionary entry on Quadrant.