What does subset mean?
A subset is a set whose members all belong to some larger set. In mathematics, this relationship is written with the subset symbol, and a subset may contain no elements, all the elements of the original set, or any number between those possibilities. Outside mathematics, the word refers to a selected portion of a larger group or collection, such as a subset of survey respondents or a subset of available data. The phrase often carries the implication that the portion has been chosen for a particular purpose or because its members share relevant characteristics. As a verb, 'to subset' means to select a portion for separate treatment, as in dividing records into a subset for closer analysis. The word is useful whenever distinction must be made between a whole collection and one carefully defined part of it.
A set containing only members of another specified set; more generally, a selected portion of a larger group or collection.
"Each rectangle is a subset of the plane."
A subset can be empty or equal to the containing set; a 'proper subset' contains some, but not all, of the original set's elements.
To select a portion of a group, collection, or dataset for separate consideration or treatment.
"We subset the records by region before analyzing them."
This is mainly used in technical, academic, and data-processing contexts.
The plural is 'subsets'.
"The course draws on several subsets of the available evidence."
In mathematics, a subset can be part of a set without sharing any elements with it at all.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does subset come from?
The word combines the Latin-derived prefix 'sub-' meaning 'under' or 'beneath' with 'set', an English noun inherited from Old English. 'Subset' was adopted in mathematics during the modern period as a translation of the German term 'Teilmenge'. Its general sense of a selected portion developed from the mathematical sense.
Related word forms
How subset is actually used
In mathematical writing, the phrase 'a subset of' does not by itself imply that the subset is a proper subset; it may equal the original set. In general usage, 'subset' often suggests a selected or smaller portion, though it need not be strictly smaller. As a verb, 'subset' is relatively technical and is less common than the noun.
Easily confused with subset
A subset contains only elements also found in the larger set, whereas a superset contains every element of the original set and may contain additional elements.