infiltrated

Infiltrated is the past participle and adjective derived from the verb infiltrate. It describes something that has entered or gained access to a space, organization, tissue, or system in a secret, gradual, or covert manner. The term is commonly used across fields to indicate penetration or occupancy by external agents, substances, or elements.

Etymology: from Latin infiltratus, from infiltrare, to creep or leak in.

Usage in security and intelligence: In espionage or security contexts, a person or group that has successfully penetrated an organization may be described as infiltrated, and operations may be described as infiltrated networks or infiltrated cells. Infiltration is the act; an infiltration outcome informs assessments of risk and defensive posture.

Biology and medicine: In pathology, "infiltrated" often refers to tissue that has been populated by cells or substances, such as inflammatory cells infiltrating tissue, or cancer cells that have infiltrated surrounding tissues (invasive carcinoma). It is distinct from acute edema or exudate. In microscopy, infiltrated immune cells are observed as signs of inflammation or immune response.

Environmental and physical processes: In hydrology and geology, infiltration describes the process by which water or other liquids enter the soil or rock. Descriptions may say a soil has been infiltrated by water, and the infiltration rate indicates how quickly this occurs, influenced by soil type, moisture, and surface conditions.

Technology and cybersecurity: In digital security, attackers aim to infiltrate a network or system. Systems that have been compromised are described as infiltrated, with activity suggesting a breach, persistence, and potential data exfiltration.