clean

Etymology

From Middle English clene, clane, from Old English clǣne (“clean, pure”), from Proto-West Germanic *klaini, from Proto-Germanic *klainiz (“shining, fine, splendid, tender”), from Proto-Indo-European *glēy- (“gleaming”), from Proto-Indo-European *gel- (“to gleam”). Cognate with Scots clean (“absolute, pure, clear, empty”) and clene, clane (“clean”), North Frisian klien (“small”), Dutch klein (“small”), Low German kleen (“small”), German klein (“small”), Swedish klen (“weak, feeble, delicate”), Icelandic klénn (“poor, feeble, petty, snug, puny, cheesy, lame”).

adj

1. (physical) Free of dirt or impurities.
   1. Not dirty, filthy, or soiled.
      Are these dishes clean? Your room is finally clean! For a baby, happiness is a full bottle and a clean diaper.
   2. In an unmarked condition.
      Put a clean sheet of paper into the printer.
   3. (aerodynamics) Allowing an uninterrupted flow over surfaces, without protrusions such as racks or landing gear.
   4. (aviation) Having the undercarriage and flaps in the up position.
   5. Empty.
      The cargo hold is clean.  Mister, I want to see a clean dinner plate or there'll be no dessert for you.
   6. (of metal) Having relatively few impurities.
      clean steel
2. (behavioural) Free of immorality or criminality.
   1. Pure, especially morally or religiously.
      Our kids can watch this movie because it is clean.
      I do not think there is any member in this House who will not agree that that is the clean thing to do. Any member sitting on the Government benches will admit in private that that is the proper course for members who break faith. 1914, Parliamentary Debates, volume 168, New Zealand, page 195
   2. Not having used drugs or alcohol.
      I've been clean this time for eight months.
   3. (of criminal, driving, etc. records) Without restrictions or penalties, or someone having such a record.
      Unlike you, I’ve never caused any accidents — my record is still clean!
   4. (informal) Not in possession of weapons or contraband such as drugs.
      I'm clean, officer. You can go ahead and search me if you want.
   5. (informal) Devoid of profanity.
3. Smooth, exact, and performed well.
   I'll need a sharper knife to make clean cuts.  a clean leap over a fence
4. (obsolete) Total; utter. (still in "clean sweep")
5. (informal) Cool or neat.
   Wow, Dude, those are some clean shoes ya got there!
6. (health) Being free of sexually transmitted diseases (STDs).
   I want to make sure my fiancé is clean before we are married.
7. That does not damage the environment.
   clean energy;  clean coal
8. Free from that which is useless or injurious; without defects.
   clean land;  clean timber
9. Free from restraint or neglect; complete; entire.
10. Well-proportioned; shapely.
    clean limbs
11. (climbing, of a route) Ascended without falling.

noun

1. Removal of dirt.
   This place needs a clean.
2. (weightlifting) The first part of the event clean and jerk in which the weight is brought from the ground to the shoulders.