English Reference
verb

penetrate

v.
US /ˈpɛnəˌtɹeɪt/ UK /pˈɛnɪtɹˌeɪt/ pen·e·trate UK spelling penetrated, penetrates

  1. 01 B2 Upper Intermediate

    to go into or through something, especially when it is hard or thick.

    to pass into or through the substance of something; to pierce or enter the interior.

    Simple

    The rain managed to penetrate his thick winter coat after an hour outside.

    In context

    The new drill bit was designed specifically to penetrate reinforced concrete without overheating or dulling the cutting edge.

    Usage

    Often used with a direct object or with the preposition 'into'.

    pierceenterperforate
  2. 02 C1 Advanced Formal

    to succeed in understanding something that is difficult or hidden.

    to grasp the inner meaning or nature of something complex; to see through a mystery or obstacle.

    Simple

    Scientists are still trying to penetrate the mysteries of how the brain works.

    In context

    Despite years of intensive research, historians have struggled to penetrate the motives behind the king's sudden and unexplained abdication.

    Usage

    Usually takes a direct object like 'mystery', 'meaning', or 'mind'.

  3. 03 C1 Advanced AcademicFormal

    to enter a group or organization secretly to get information.

    to gain access to an organization or enemy territory, typically for the purpose of gathering intelligence or influence.

    Simple

    The undercover agent managed to penetrate the criminal gang over several months.

    In context

    The intelligence agency successfully penetrated the network, allowing them to monitor communications for several months before making any arrests.

    Usage

    Common in political, military, or corporate contexts.

    infiltratepermeate
  4. 04 C1 Advanced TechnicalFormal Medicine

    to insert the penis into a partner's body during sex.

    to insert the penis into a body orifice; used in clinical, legal, or descriptive sexual contexts.

    Simple

    The doctor explained the risks of infection during any kind of sexual penetration.

    In context

    The legal definition of the act requires proof that the defendant intended to penetrate the victim without consent.

    Usage

    Used as a transitive verb in medical or legal documentation.

  5. 05 C2 Proficiency Literary

    to have a very strong effect on someone's feelings.

    to affect or move someone profoundly through the senses or emotions.

    Simple

    The sad music seemed to penetrate her very soul.

    In context

    The cold dampness of the cathedral seemed to penetrate his bones, adding to the somber mood of the funeral service.

Researchers have found a way to supercharge natural killer cells, powerful immune cells that can attack cancer, so they can penetrate solid tumors and keep fighting once inside.

ScienceDaily· 25 Aug 2026

The UV Index is usually lower on cloudy days, but even so, solar radiation can penetrate through the clouds.

The Local· 12 Aug 2022

From Latin penētrātus, perfect passive participle of penētrō (“to put, set, or place within, enter, pierce, penetrate”) (see -ate (verb-forming suffix)), from penes (“within, with”) by analogy to intrō (“to go in, enter”). Compare French pénétrer.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry
Origin Latin penētrātus
Level B2 · Upper Intermediate
Frequency Frequent
Updated