The Collaborative International Dictionary of English v.0.48:

Gabbro \Gab"bro\, n. [It.] (Geol.)
   A name originally given by the Italians to a kind of
   serpentine, later to the rock called euphotide, and now
   generally used for a coarsely crystalline, igneous rock
   consisting of lamellar pyroxene (diallage) and labradorite,
   with sometimes chrysolite (olivine gabbro).
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Euphotide \Eu"pho*tide\, n. [Gr. e'y^ well + ?, ?, light. So
   called because of its pleasing combination of white and
   green.] (Min.)
   A rock occurring in the Alps, consisting of saussurite and
   smaragdite; -- sometimes called gabbro.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gabbro
    n 1: one of a family of granular intrusive rocks