To permeate is to pass or spread through something.

// The scent of lilacs permeated the room.

// A feeling of anxiety permeated the office as everyone rushed to meet the deadline.

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"The smell of sawdust permeates the air, and the din of buzzing chainsaws echoes from crews working to clear debris." — Chris Boyette, CNN, 3 Oct. 2024

Permeate was borrowed into English in the 17th century from Latin permeatus, which comes from the prefix per- ("through") and the verb meare, meaning "to go" or "to pass." Meare hasn't exactly permeated English. Aside from permeate itself, its other English descendants include the relatively common permeable as well as the medical meatus ("a natural body passage") and the downright rare irremeable ("offering no possibility of return").