the.com/null set

means The empty set — a well-defined collection that contains exactly zero elements, but still counts as a legitimate set in mathematics.

from "Null" traces back to Latin nullus, "none, not any" (ne- "not" + ullus "any"), the same root that gives us "annul" and "nullify." "Set" as a mathematical term took hold in the late 1800s, largely through Georg Cantor's work founding set theory. Pairing them gave mathematicians a precise way to name the strange but necessary case of a set with nothing in it — not nothing itself, but a formal container for nothingness, as real to the theory as any set brimming with members.