pénétration

Pénétration is a term with roots in Latin penetrare meaning "to enter through." In French, pénétration denotes the act or process of entering, breaching, or passing through a boundary, barrier, or surface. The term is used across disciplines to describe the extent to which something can enter another substance or space, or the degree of influence or understanding.

In physical sciences and engineering, penetration describes how far a particle, wave, or signal can advance into a material before it is absorbed or scattered. Examples include optical or X-ray penetration, where material properties determine the depth, and ballistic or radiation penetration, referring to how far a projectile or radiation can traverse a medium.

In biology and medicine, penetration refers to the entry of substances or organisms into tissues. It encompasses skin or mucous membrane penetration by drugs, topical formulations, or pathogens, as well as cellular uptake and drug-delivery systems. Penetration depth can influence efficacy, distribution, and safety.

In information technology, penetration testing, or pentesting, is a controlled practice in which authorized testers simulate cyberattacks to identify vulnerabilities and improve defenses. In other fields, penetration can describe breaching barriers such as armor, soil, or cultural boundaries, and, in sexual health contexts, denotes the act of insertion during sexual activity.