The Collaborative International Dictionary of English v.0.48:

Dirigent \Dir"i*gent\, a. [L. dirigens, p. pr. of dirigere. See
   Direct, a.]
   Directing. --Baxter.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dirigent \Dir"i*gent\, n. (Geom.)
   The line of motion along which a describent line or surface
   is carried in the genesis of any plane or solid figure; a
   directrix. --Hutton.
   [1913 Webster]