"to flow as ooze, percolate through the pores of a substance" (intrans.), also "emit in the shape of moisture" (trans.), late 14c., wosen, verbal derivative of Old English noun wos "juice, sap," from Proto-Germanic *wosan (source of Middle Low German wose "scum"), from same source as ooze (n.). The modern spelling is from late 16c. The Old English verb was wesan. Related: Oozed; oozing.