infiltrates; infiltrated; infiltrating
1
a
: to secretly enter or join (something, such as a group or an organization) in order to get information or do harm
The gang was infiltrated by undercover agents.
—sometimes used figurativelyAn attitude of cynicism has infiltrated the staff. [=the staff has become cynical]
b
: to cause (someone) to secretly enter or join a group, organization, etc.
Attempts to infiltrate undercover agents into the gang have failed.
2
technical
: to pass into or through (something)
Water can easily infiltrate the soil.
Cite this Entry
“Infiltrate.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/infiltrate. Accessed 15 Apr. 2026.
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