Nonpermeable

Part of speech: adjective

Definitions

1. Characterized by a material's inability to allow any substances to pass through it
2. Describes a material that completely blocks the passage of liquids or gases
3. Refers to a surface or membrane impermeable to any flow of substances

Etymology: "Nonpermeable" is a plain compound: the prefix "non-", meaning "not", attached to "permeable". That English prefix descends from the Old English "nān", meaning "none" or "not one," which over centuries shrank into a negating element and was then reused freely to form new words. "Permeable" is the older and more interesting half. It comes from Latin "permeare," "to pass through," built from "per," "through," and "meare," "to go." A permeable material is one that lets something pass through its pores or gaps, so a nonpermeable material is one that stops that passage entirely, whether the thing passing is water, air, or some other fluid. Because the prefix is attached to an existing adjective, the word is best understood as a straightforward negation rather than a separate coinage. Its meaning follows directly from combining the two parts.

Synonyms: impermeable, sealed, watertight, airtight, dense

Antonyms: permeable, porous, penetrable, leaky, open