polyembryony

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. Development of more than one embryo from a single egg or ovule.

Century Dictionary and Cyclopedia

1. n. In botany, the production or existence of two or more embryos in one seed—a phenomenon occurring, sometimes regularly and sometimes abnormally, in the development of the ovules of flowering plants. In angiospermous plants several germinal masses usually occur in the unfertilized embryosac, but in most cases only one of these is impregnated, and, although occasionally more than one commence the course of development, as in the Orchideæ, generally all but one become subsequently obliterated. In the orange, however, this is not the case, and its ripe seeds are met with containing more than one embryo.

Wiktionary

1. n. botany The production of two or more embryos in one seed, due either to the existence and fertilization of more than one embryonic sac or to the origination of embryos outside of the embryonic sac.

GNU Webster's 1913

1. n. (Bot.) The production of two or more embryos in one seed, due either to the existence and fertilization of more than one embryonic sac or to the origination of embryos outside of the embryonic sac.