hollowness

Hollowness is the state or quality of having an interior space that is empty or largely empty. It can describe physical cavities in objects as well as figurative emptiness in experience or meaning. The term is used across disciplines to denote an absence of matter, substance, or content in a given context.

In the physical world, hollowness appears in natural forms such as caves, tree trunks, bones with marrow, and seeds with pith. It also describes manufactured items with empty interiors, like pipes, shells, jars, and hollow-core panels. A hollow form reduces weight and can provide space for storage, insulation, or fluid flow, but it can weaken structural strength and complicate load-bearing design.

In materials science and engineering, hollow structures such as tubes, shells, and nanospheres offer high surface area and low density. Manufacturing methods include molding, etching, electrochemical dissolution, and additive manufacturing. Applications span energy storage, catalysts, acoustics, insulation, and lightweight construction.

In psychology and philosophy, hollowness can describe a subjective feeling of emptiness, meaninglessness, or alienation. It figures prominently in existential thought and modern literature, where it is linked to questions of identity and purpose. The concept is often discussed in cultural critique of consumerism and social dislocation.

Etymology: the term derives from Old English holh, meaning hollow or recess, with cognates in other Germanic languages. It is related but not synonymous with cavity, void, or emptiness.