Myrtaceous \Myr*ta"ceous\, a. [L. myrtaceus.]

(Bot.) Of, pertaining to, or resembling, a large and important natural order of trees and shrubs (Myrtace[ae]), of which the myrtle is the type. It includes the genera Eucalyptus, Pimenta, Lechythis, and about seventy more.

Source: Webster's Revised Unabridged Dictionary (1913)