fertilise
variants or British fertilisation
ˌfərt-ᵊl-ə-ˈzā-shən
: an act or process of making fertile: as
Noun
a
: an act or process of fecundation, insemination, or impregnation
b
: the process of union of two gametes whereby the somatic chromosome number is restored and the development of a new individual is initiated
Source