infiltrado
/infilˈtɾado/ · B2 · noun · m
infiltrator
🕵️ in- (into) + filtrar (to filter): seeps in like water through a filter
Infiltrado comes from in- (into) plus filtrar (to filter, seep). An infiltrator is someone who passes through the barrier slowly and unnoticed, the way liquid trickles through a filter. Compare English infiltrate, which shares the same root.