The Collaborative International Dictionary of English v.0.48:

Irrorate \Ir"ro*rate\, v. t. [imp. & p. p. Irrorated; p. pr. &
   vb. n. Irrorating.] [L. irroratus, p. p. of irrorare to
   bedew; pref. ir- in + ros, roris, dew.]
   To sprinkle or moisten with dew; to bedew. [Obs.]
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Irrorate \Ir"ro*rate\, a. (Zool.)
   Covered with minute grains, appearing like fine sand.
   [1913 Webster]