1. A fixed line used in describing a curve or a surface: A directrix is a specific line used in constructing a curve or conic section, the distance from the line divided by the distance from a set point being identical for all points on the figure.
2. A woman who directs; directress: Mrs. Hathaway, the directrix of the firm, was respected by all of the workers, regardless of age, gender, or race.

A woman who is a director or a directress; that is, a female who is in charge of an activity, department, or organization; such as, the sales directrix of the department store.