praesertim

Praesertim is an adverb built on the root of sero, "I join in a row", with prae in front: the thing set at the head of the line. It singles one item out of a group already mentioned, so it needs that group to be there. You cannot open a paragraph with praesertim the way English can open with "particularly".

It is at its most useful with cum. Praesertim cum plus the subjunctive means "especially since", and it is the standard way Cicero adds a clinching reason at the end of an argument. Compare its neighbours: maxime is "most of all" on a scale, praecipue marks something as taking precedence, potissimum picks the preferred option. Praesertim is the one that says "and this case above the rest". No English derivative.