If you want to look up this term in the dictionary—or better yet, an encyclopedia—you should look at the disambiguates “Apartheid (Crime against humanity)” or “Apartheid (International humanitarian law)” in which case you’ll probably be referred to the Rome Statute Part 2, Article 7, Paragraph 2(h):
> "The crime of apartheid" means inhumane acts of a character similar to those referred to in paragraph 1, committed in the context of an institutionalized regime of systematic oppression and domination by one racial group over any other racial group or groups and committed with the intention of maintaining that regime;
Israel does segregate inside the territories they control, and the inhabitants of some of those territories are predominantly of one racial group (Palestinian Arabs), which suffers systematic oppression and domination by another racial group (Israeli Jews). The practices and policies of Israel in its occupied territories do constitute a Crime against humanity, and in particular, the crime of Apartheid. I will refer to an ongoing ICJ case 186[1] which lists these accusations and how they constitute a crime against humanity. In particular the South Africa testimony[2] (Page 36, Paragraph 93)
> While the Palestinian experience is not entirely identical to the South African one, a number of apartheid-style atrocities are being reproduced in Palestine, such as the permit system which applies only to Palestinians travelling to and from the Gaza Strip, annexed East Jerusalem and the rest of the West Bank. This includes the creation of a dual legal system consisting of an intricate and obscure system of military orders and regulations, which “often racialised in implementation rather than on paper makes the depth of Israel’s systematic discrimination less immediately conspicuous than its counterpart in South Africa”.
1: https://www.icj-cij.org/case/186
2: https://www.icj-cij.org/sites/default/files/case-related/186...