permeant (adj.)

early 15c., "passable" (of an area); "penetrable" (of a building)," from Late Latin permeabilis "that can be passed through, passable," from Latin permeare "to pass through, go over," from per "through" (from PIE root *per- (1) "forward," hence "through") + meare "to pass," from PIE root *mei- (1) "to change, go, move." Meaning "capable of being passed through without rupture or displacement" is from 1773, especially of substances permitting the passage of fluids. Related: Permeably.