Source : Webster's Revised Unabridged Dictionary (1913)

Rosaceous \Ro*sa"ceous\, a. [L. rosaceus, fr. rosa rose.]
   1. (Bot.)
      (a) Of or pertaining to a natural order of plants
          ({Rosace[ae]}) of which the rose is the type. It
          includes also the plums and cherries, meadowsweet,
          brambles, the strawberry, the hawthorn, applies,
          pears, service trees, and quinces.
      (b) Like a rose in shape or appearance; as, a rosaceous
          corolla.

   2. Of a pure purpish pink color.

Source : WordNet®

rosaceous
     adj 1: of or pertaining to or characteristic of plants of the
            family Rosaceae
     2: having a dusty purplish pink color; "the roseate glow of
        dawn" [syn: {rose}, {roseate}]