An amorphous material is one that displays properties of both a solid and a liquid. Mayonnaise is an example of an amorphous substance, since it exhibits liquid properties but the molecules are so arranged that it can withstand stress.
Human tissue is also an example of an amorphous material. The disorganized nature of human tissue means there is no common center of mass for each cell. Amorphous materials can tolerate yield stress to some degree, which is what human tissue exhibits.
A lack of organization also means the amorphous material is likely to deform under pressure. This contrasts with wood that has a solid structure and does not deform under pressure.
Other examples of amorphous materials include foam, emulsions and sand.