Holocaust, as defined by Merriam Webster: 3 (a) often capitalized : the mass slaughter of European civilians and especially Jews by the Nazis during World War II —usually used with "the" (b) : a mass slaughter of people; especially : genocide.
Foeticide, a term coined between 1835 and 1845, was the word used to refer to an abortion, as the word "abortion" was considered inappropriate until the mid 20th century. When discussed in print the preferred term was "criminal operation".
It could be argued that large numbers of foeticides, or abortions, are a type of genocide. In most genocide, discrimination is on the basis of politics or race, in abortion, age is the factor considered.