# nLab 3-morphism

### Context

#### Higher category theory

higher category theory

# Contents

## Definition

A 3-morphism in an n-category is a morphism between 2-morphisms.

## Examples

For $A$ an abelian group, the 3-fold delooping ${B}^{3}A$ is a 3-groupoid whose 3-morphisms are given by $A$.

Revised on September 11, 2010 10:33:26 by Urs Schreiber (188.20.66.18)