A small sample of fabric or a book of small fabric samples tied or pinned together. Now more commonly called cutting or cuttings.
A swatch or cutting is usually about 10 x 15 cm and as such is useful enough to see the colour and weave or print. You can tell much about the fabric from a cutting. However, it’s not enough to order from as you always need to feel it, to know how it will be to touch and to sit on, to drape it and see how the colour is affected by light and how the material responds to creasing and to water marks.