läpäisemättä

läpäisemättä is a Finnish adverbial participle derived from the verb läpäistä, meaning to penetrate or pass through. The form carries a negative nuance by using the suffix -mättä, and translates roughly as “without passing through” or “without penetrating.” It is used to describe an action that does not cross a barrier or medium, or to characterize a barrier as impermeable in a given process.

In technical and scientific language, the word appears in fields such as optics, acoustics, materials science, and engineering to specify whether a material, shield, or medium allows passage of a substance, wave, or signal. The related noun läpäisemättömyys expresses impermeability or opacity. The word is typically used with verbs in the negative sense, for example with ei to indicate that something cannot pass through.

Usage is more common in written, formal, or technical contexts than in everyday speech. It can modify a clause or an action, and it is part of Finnish grammatical patterns that convey manner or condition of passage.

See also: läpäisy, läpäisemättömyys, läpäisevä, läpäisykyky.