In reproductive biology, union of male and female gametes to form a zygote from which an embryo can develop.
See also: conception
Source:
PAC, 2016, 88, 713. 'Glossary of terms used in developmental and reproductive toxicology (IUPAC Recommendations 2016)' on page 754 (https://doi.org/10.1515/pac-2015-1202)