In general, the term fabric describes the way different parts of something work together to form a single entity. In information technology, fabric is used as a metaphor to illustrate the idea that if someone were to document computer components and their relationships on paper, the lines would weave back and forth so densely that the diagram would resemble a woven piece of cloth.
The term fabric is commonly used to describe data or storage area networks (SANs). Increasingly, however, vendors are using the term to describe the servers, high-speed connections and switches that make up a cloud computing platform.
Continue reading about fabric:
Steven Nagy answers the question What is the Azure Fabric and the Development Fabric?
When referring to Fibre Channel networks, what does "fabric" mean?
Here is a SearchStorage.com definition of network fabric.