The Collaborative International Dictionary of English v.0.48:

Embryo \Em"bry*o\, a.
   Pertaining to an embryo; rudimentary; undeveloped; as, an
   embryo bud.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Embryo \Em"bry*o\, n.; pl. Embryos. [F. embryon, Gr.
   'e`mbryon, perh. fr. ? in (akin to L. ? E. in) + ? to be full
   of, swell with; perh. akin to E. brew.] (Biol.)
   The first rudiments of an organism, whether animal or plant;
   as:
   (a) The young of an animal in the womb, or more specifically,
       before its parts are developed and it becomes a fetus
       (see Fetus).
   (b) The germ of the plant, which is inclosed in the seed and
       which is developed by germination.
       [1913 Webster]

   In embryo, in an incipient or undeveloped state; in
      conception, but not yet executed. "The company little
      suspected what a noble work I had then in embryo."
      --Swift.
      [1913 Webster]

WordNet (r) 3.0 (2006):

embryo
    n 1: (botany) a minute rudimentary plant contained within a seed
         or an archegonium
    2: an animal organism in the early stages of growth and
       differentiation that in higher forms merge into fetal stages
       but in lower forms terminate in commencement of larval life
       [syn: embryo, conceptus, fertilized egg]