impermeável

Impermeável is an adjective in Portuguese that describes the property of resisting the passage of liquids, especially water. It can also be used as a noun to refer to a raincoat or waterproof coat, commonly called o impermeável. When applied to fabrics, coatings or membranes, a material described as impermeável is designed to prevent water infiltration, though some products allow controlled diffusion or vapor transmission.

Etymology and general usage: the word comes from the prefix im- (not) added to permeável (permeable), which derives from Latin permeabilis. The concept is used across disciplines such as clothing, construction, and science to indicate resistance to liquid permeation.

Contexts and applications: in everyday language, impermeável refers to clothing like casaco impermeável or capa impermeável, as well as to building materials and coverings designed to keep water out. In construction, impermeabilização is the process of making surfaces watertight, using membranes, coatings, sealants and protective layers, while impermeabilizante denotes a product that provides this property.

Geology, engineering and biology: in geology and civil engineering, an impermeável layer or barrière restricts fluid flow, helping to contain groundwater or protect foundations. In biology and medicine, impermeável describes membranes or barriers that do not permit passage of certain substances, contributing to selective permeability of cells or tissues.

Related terms and contrasts: impermeável contrasts with permeável (permeable) and poroso (porous). Related concepts include impermeabilizante (a substance that provides impermeability) and impermeabilizar (to apply a waterproofing layer).