An embryo is an unborn animal or human being in the very early stages of development.
e.g. The embryo lives in the amniotic cavity.
e.g. ...the remarkable resilience of very young embryos.
An embryo idea, system, or organization is in the very early stages of development, but is expected to grow stronger.
e.g. They are an embryo party of government...
e.g. It was an embryo idea rather than a fully worked proposal.
Something that is in embryo is at a very early stage of its development.
e.g. These developments were foreseen in embryo more than a decade ago.