What does the term porous mean?

The term "porous" refers to a material that is made or constructed with openings or tiny spaces that allow air or liquid to pass through. This characteristic is important in various fields, including esthetics, as it can affect how products are absorbed by the skin or how they interact with other materials. For example, a porous sponge can soak up liquids due to its many openings, making it effective for application in beauty treatments.

In contrast, the other options describe materials in ways that are inconsistent with the definition of porous. Describing a material as thick and solid or dense and heavy suggests that it is compact and lacks openings. Being completely airtight implies that the material does not allow any flow of air or liquid, which is the exact opposite of porous. Thus, the only definition that aligns with the meaning of the term "porous" is that it is made or constructed of a material with openings.