The Children and Family Relationships Act 2015, in the context of Parts 2 and 3 of that Act, which relate to donor-assisted human reproduction (DAHR), defines an embryo as "a human embryo formed by the fertilisation of a human egg by a human sperm".
As the Deputy will be aware, officials in my Department are currently drafting the General Scheme of legislative provisions relating to the area of assisted human reproduction as a whole. The provisions in the General Scheme, including particular definitions, will, where relevant, be consistent with the provisions of the Children and Family Relationships Act 2015.