# accumulation point

## English

### Noun

accumulation point (plural accumulation points)

1. (topology) (said to be "of" a given subset of a topological space) a point whose every neighborhood contains infinitely many points belonging to the given subset
• 1975, Bert Mendelson, Introduction to Topology, Third edition, New York: Dover Publications, Inc., published 1990, →ISBN, OCLC 932232056, §5.3, page 173:
LEMMA 5.2    Let X be a Hausdorff space and A a subset of X. A point ${\displaystyle a\in X}$ is an accumulation point of A if and only if a is a limit point of A.