haecceity, n.
(haecceities)
the essence that makes something the kind of thing it is and makes it different from any other
<noun.cognition>
haecceity
quiddity
semantic pointers
hypernym
center, substance, core, essence, heart, sum, kernel, centre, gist, heart and soul, inwardness, marrow, meat, nub, pith, nitty-gritty