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.