Directrix

1 definition found

From The Collaborative International Dictionary of English v.0.48 [gcide]:

  Directrix \Di*rect"rix\, n.; pl. E. {Directrixes}, L.
     {Directrices}.
     1. A directress. [R.] --Jer. Taylor.
        [1913 Webster]
  
     2. (Geom.)


        (a) A line along which a point in another line moves, or
            which in any way governs the motion of the point and
            determines the position of the curve generated by it;
            the line along which the generatrix moves in
            generating a surface.
        (b) A straight line so situated with respect to a conic
            section that the distance of any point of the curve
            from it has a constant ratio to the distance of the
            same point from the focus.
            [1913 Webster]