Not evitable; incapable of being shunned; unavoidable; certain.

an unavoidable event; "don't argue with the inevitable"

incapable of being avoided or prevented; "the inevitable result"

Irresistible.

a miscarriage that cannot be halted;

miscarriage(IMC) Traditionally any bleeding from the vagina during early pregnancy with, on vaginal examination, opening of the cervix. Today, the diagnosis can be made much sooner (and distinguished from a threatened miscarriage) by not detecting a normal embryo in a gestational sac on transvaginal ultrasound. Management is similar to the management of an incomplete miscarriage, often requiring curettage (and both are abbreviated IMC).

invariably occurring or appearing; "the inevitable changes of the seasons"

In the Dungeons & Dragons role-playing game, inevitables are extraplanar magical constructs.