Answer: infiltrating

AnswerCrossword Clue
infiltrating(of a liquid) Permeate (something) by filtration
infiltratingPermeate or become a part of (something) in this way
infiltratingEnter or gain access to (an organization, place, etc.) surreptitiously and gradually, esp. in order to acquire secret information
infiltratingINFILTRATE, to cause to filter into
infiltrating(of a tumor, cells, etc.) Spread into or invade (a tissue or organ)
infiltratingIntroduce (a liquid) into something in this way