penetra-, penetr-

1. That which is impossible to pierce, to get into, or to get through: The wall was impenetrable despite all of the bullets that were fired into it.

The thorny branches made a thick, impenetrable hedge around Helena's house.

2. A reference to something that is inconceivable to understand or to explain: Lee was reading about what the police declared to be an impenetrable crime.

The students couldn't comprehend the teacher's impenetrable explanation of the mathematical processes.

3. Not open to ideas, impressions, influences, etc.: Ingrid had an impenetrable mind and so she would not change her opinions regarding how to proceed with the project.
4. Etymology: borrowed through Middle French impenetrable; from Latin impenetrabilis, from im-, "not, opposite of", a variant of in- before p + penetrabilis, "put into, get into, enter into".

Incomprehensibility because of great difficulty in grasping what is going on or what is being said: The impenetrableness of what the speakers on the TV program were trying to present was very frustrating.

1. That which is too difficult to accomplish or to go through: While camping in the forest, Jerry had to use a flashlight in order to get around in the impenetrably dark night.
2. A reference to something that is beyond one's power to discern: As a reporter, Shelby was having a problem interviewing the more impenetrably non-English speaking refugees.

In geology, a type of deformation, affecting only part of a rock: The nonpenetrative texture of a rock is caused by slippage or movements.

The extent to which something is conceived clearly and fully: As a writer, Debora had a special penetrability that was greatly admired by her readers.

1. A reference to something that is able to permeate into or to go through something: The rebels used penetrable ammunition against the government forces.
2. Having or showing an ability to figure out things clearly and fully: Dr. Rosetta Bradley had penetrable insights regarding the medical condition of her patient.

The innermost parts of a building; especially, of a temple or sanctuary: In Roman times, the penetralia were the parts of a Roman temple to which the priests alone had access, where the sacred images were kept, the responses of the oracles were made, and the sacred mysteries were performed.

The holy of holies was the penetralia of the Jewish Temple or the sanctuary that consisted of the innermost chamber of the Tabernacle in the temple of Solomon where the Ark of the Covenant was kept.

1. A person or something that can puncture or pierce: Floyd had penetrants that were powerful arguments against the policies of the current company president.
2. A compound that goes through or into something: The pharmacist recommended a lotion for Leon's skin that could function as a penetrant to relieve the itching.
3. A large capsule that discharges and injects a toxic fluid: The jellyfish uses a penetrant containing a barbed, threadlike tube, that delivers a paralyzing sting into its attackers or prey.

A reference to someone or something which is sharp and that has the power to break in or to force its way into a place or a situation: The penetrant cold weather was difficult to live in because of the penetrant wind from the north.

A penetrant liquid is one that usually contains a dye or fluorescent chemical which, when poured over a metal surface, determines the existence of cracks.

1. To go into, to burst in upon, to force a way into, or to bore into: The constant sounds from the playing of Mike's electric guitar penetrated all of the rooms in the house.

The nails easily penetrated the soft wood when Kyle was working on his carpentry project.

The odor of garlic penetrated the entire apartment when Debora was cooking.

2. To force one's way in, go into, or to pass through: Melvin's eyes couldn't penetrate the darkness.

Even where the trees were thickest, the sunshine still penetrated through the leaves.

3. To get into an enemy group or rival organization to obtain information or to influence some kind of changes: Polly and Helena decided to penetrate the political group so they could find out what the organization was planning against their opposition.

The government fears that there are informers who are penetrating the special military department so they can publicize its secret activities.

4. To succeed in fathoming or gaining insight into something complex or mysterious: John, the biologist, apparently was able to penetrate the mysteries of nature.

1. A reference to that which permeates or pervades: Ammonia has an extremely penetrating odor.
2. Sharp-witted, perceptive, showing insight, or discerning: As a reporter, Eugenia was making a penetrating study of the political proposals of the two candidates.

Susana made penetrating criticisms about her company's labor policies.

A digging or soil removal technique that is used in archaeology to expose the vertical face of a site: The archeologists used the latest penetrating excavation techniques to uncover the ancient Greek wall during their latest exploration.

An impact crater formed by a small meteorite that strikes the earth at a relatively low speed and which contains nearly all of the impacting mass within it: The astronomers were fascinated by the penetrating funnels which were discovered after the meteorite shower during the summer.

Damage or a wound that is caused by a sharp object: Grover, the carpenter, was rushed to the hospital after suffering from penetrating injuries when he fell on a board with nails sticking up and penetrated into his backside and into the underlying tissues of his skin.

A low-viscosity oil that can go between closely fitted parts; such as, parts of rusty springs and screw threads: The penetrating oil is used to loosen rusted parts so they can function properly again or be easier to replace.