intromission
noun
in·tro·mis·sion ˌin-trə-ˈmi-shən 
: the act or process of intromitting
especially : the insertion or period of insertion of the penis in the vagina in copulation
Word History
Etymology
French, from Middle French, from Medieval Latin intromission-, intromissio, from Latin intromittere
First Known Use
1601, in the meaning defined above
Medical Definition
intromission
noun
in·tro·mis·sion ˌin-trə-ˈmish-ən
: the insertion or period of insertion of the penis in the vagina in copulation