1. A way to approach a structure or area in order to obtain secret information. A competing company has obtained the results of the profits for the year of another commercial business.
2. A number of cells in the body that have been affected by a disease: A chest radiograph revealed patchy infiltrates in Michael's lungs.

1. To enter or to gain access to an organization, place, etc. secretly and gradually; especially in order to acquire secret information or to do harm: The criminal organization was infiltrated by undercover agents of the FBl.

The government infiltrated key enemy agencies with spies.

Some cybercriminals are infiltrating the contents of Internet sites in order to collect system profile data so the bad guys need to find ways to reach prospective victims and collect information about them in order to make sure targeted attacks are successful.

2. To accumulate substances or cells within a tissue that are either not normally found it it or are usually present only in smaller amounts: A drug; such as, a local anesthetic that has been into a tissue.

Excessive alcohol consumption can infiltrate the body and cause fat in the liver.

Radiologists use infiltrated to refer to the presence of a tumor or pneumonia in a tissue; such as, lung cancer as seen in a chest X-ray.