seepage (n.)

"ooze or percolate gently through pores," 1790, a variant of sipe (c. 1500), which is perhaps ultimately from Old English sipian "to seep," from Proto-Germanic *sip- (source also of Middle High German sifen, Dutch sijpelen "to ooze"), from PIE root *seib- "to pour out, drip, trickle" (see soap (n.)). Related: Seeped; seeping.

word-forming element in nouns of act, process, function, condition, from Old French and French -age, from Late Latin -aticum "belonging to, related to," originally neuter adjectival suffix, from PIE *-at- (source of Latin -atus, past participle suffix of verbs of the first conjugation) + *-(i)ko-, secondary suffix forming adjectives (see -ic).