Mid 18th century: from Italian (Neapolitan dialect), denoting the lava stream from Vesuvius, but originally denoting a stream caused by sudden rain, from lavare 'to wash', from Latin.

• launder from Middle English:

  In the sense ‘to wash clothes or linen’, launder was originally a contracted form of lavender, a medieval word meaning ‘a person who washes clothes’. It goes back to Latin lavare to wash, the source of lava (mid 18th century) originally an Italian word for ‘steam’ narrowed down to mean a stream of lava; lavatory (Late Middle English); and lavish (Late Middle English) where the sense of ‘profusion’ comes from the French for a deluge of rain; and lotion (Late Middle English) which in the past could also be used for the action of washing as well as for a liquid rubbed on. Lavender (Late Middle English) probably does not come directly from lavare, but its form was altered to look as if it did, because lavender was used to scent washing. The Watergate scandal in the USA in the early 1970s, in which an attempt to bug the national headquarters of the Democratic Party led to the resignation of President Richard Nixon, gave the world money laundering. Before bathrooms and running water, people washed from a basin or bowl. This is what a lavatory originally was—vessel for washing. In the mid 17th century the word came to refer to a room with washing facilities, from which developed the modern sense of a toilet.