Is it ensure, insure, or assure?
"cleanse by hard rubbing," c.1200, from Middle Dutch scuren, schuren "to polish, to clean," and from Old French escurer, both from Late Latin excurare "clean off," literally "take good care of," from Latin ex- "out" (see ex-) + curare "care for" (see cure (v.)). Possibly originally a technical term among Flemish workmen in England. Related: Scoured; scouring. As a noun, 1610s, from the verb.
"move quickly in search of something," c.1300, probably from Old Norse skyra "rush in," related to skur "storm, shower, shower of missiles" (see shower (n.)). Perhaps influenced by or blended with Old French escorre "to run out," from Latin excurrere (see excursion). Sense probably influenced by scour (v.1).