Other forms: laundering, laundered, launders
To launder is to wash and press clothes properly. Launder the sheets, professionally laundered, laundering service.
It means the full job — washed, dried and pressed — which is why hotels and hospitals launder rather than wash. Money laundering is passing criminal proceeds through legitimate businesses until the source cannot be traced, and the metaphor is exact enough that the word is now used more often for that than for clothes. Note launderette, laundry; and that the Latin means to wash.
1verblaunderTo wash and press clothes properly.
“The hotel launders its guests' shirts and returns them folded the next morning.”
2verbpassTo pass criminal money through legitimate businesses.
“The gang laundered its drug money through a chain of car washes.”
launder is a washing or concealing.
Middle English lavender meant a washerwoman, from Latin lavare, to wash. The plant lavender is a different word, and launder is the verb contracted from the job.
Proto-Indo-European
*lewh₃-
Latin
lavandera
Old French
lavandiere
Middle English
lavender
English, today
launder
Contracted from Middle English lavender, from Old French lavandiere, from Latin lavandera, from Latin lavō (“to wash”).
Etymology from Wiktionary, CC BY-SA