1. entering or passing into something gradually or secretly
Usage: present participle of infiltrate
2. joining a group secretly in order to get information or cause damage
Usage: present participle of infiltrate

1. characterized by gradual entry or penetration

Examples

• Water was infiltrating through the cracks in the basement wall.
• The spy was infiltrating the enemy organization.
• Smoke began infiltrating the building through the ventilation system.
• The detective was infiltrating the criminal gang to gather evidence.
• Rain was infiltrating the tent despite the waterproof coating.
• The infiltrating cells spread throughout the tissue sample.
• Foreign agents were infiltrating government agencies.