Di*rect"rix (?), *n.*; *pl.* E.
**Directrixes** (&?;), L. __Directrices__ (&?;).
**1.** A directress. [R.] *Jer.
Taylor.*

**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.