Glossary

Set Theory – Key Terms & Definitions

Essential set theory vocabulary for IGCSE Mathematics (0580). Each term includes a clear definition and example to help you understand and remember key concepts.

set

Core

Collection of distinct objects

Example

A = {1, 2, 3, 4}

element

Core

Object in a set

Example

3 ∈ A means 3 is in A

union

Core

All elements in either set

Example

A ∪ B

intersection

Core

Elements in both sets

Example

A ∩ B

complement

Core

Elements not in the set

Example

A' means not in A

universal set

Core

Set containing all elements under discussion

Example

ξ or U

empty set

Core

Set with no elements

Example

∅ or {}

subset

Core

Every element also in another set

Example

A ⊂ B

Venn diagram

Core

Overlapping circles showing set relationships

Example

Shows union and intersection visually

n of A

Core

Number of elements in set A

Example

n(A) = 4

curly brackets

Core

Used to list set elements

Example

{1, 2, 3}

finite set

Core

Set with countable elements

Example

{1, 2, 3} has 3 elements

infinite set

Core

Set with unlimited elements

Example

Set of all integers

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Frequently Asked Questions

How many set theory terms do I need to know for IGCSE?

This glossary covers 13 key set theory terms. Focus on understanding definitions and being able to use each term in context during exams.

Are these terms for Core or Extended?

Terms are labelled as Core or Extended. Core students should focus on Core-labelled terms, while Extended students need to know all terms.

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