open set

Fetched 2026-10-26 (cache).

Synonyms: open sea, open seat, open out, open pit, open cut, openest, open seas, open sets, open text, open web

Antonyms: open sea, open seat, open out, open pit, open cut, openest, open seas, open sets, open text, open web

Related words from Datamuse; suggestions, not definitions.

Noun

1. {{lb|en|topology}} Informally, a [[set]] such that the target point of a movement by a small amount in any direction from any point in the set is still in the set; exemplified by a full circle without its boundary.
2. {{lb|en|topology|analysis|restricted to metric spaces}} A [[set]] which can be described as an (arbitrary) [[union]] of [[open ball]]s. Equivalently, a set such that for every [[point]] in it, there is an open ball centered at that point, such that that open ball is contained by the set.
3. {{lb|en|topology}} Most generally, a member of the [[topology]] of a given [[topological space]].

Source: Wiktionary · CC BY-SA 4.0 (Wiktionary dump) · cached copy, not a rewrite.