Noun
(topology, "of" a subset of a topological space) Given a subset S of a topological space X, a point x whose every neighborhood contains at least one point distinct from x that belongs to S.
Synonyms: cluster point, limit point
(mathematical analysis, "of" a sequence) Given a sequence si, a point x whose every neighborhood contains at least one element of the sequence distinct from x.
Synonyms: cluster point, limit point
(systems theory, dynamical systems, chaos theory) For certain maps, a point beyond which periodic orbits give way to chaotic ones.
Source: en.wiktionary.org