
1) Blanch 2) Blanco 3) Bleach 4) Etiolate 5) Pale 
Found on 
https://www.crosswordclues.com/clue/whiten

1) Blanch 2) Bleach 3) Bleach can do it 4) Color 5) Colour 6) Discolor 7) Discolour 8) Go pale 9) Make less dingy 10) To become white or whiter 11) To bleach or blanch 12) Turn white 13) Use stain-removing toothpaste 14) White 
Found on 
https://www.crosswordclues.com/clue/whiten

• (v. t.) To make white; to bleach; to blanch; to whitewash; as, to whiten a wall; to whiten cloth. • (v. i.) To grow white; to turn or become white or whiter; as, the hair whitens with age; the sea whitens with foam; the trees in spring whiten with blossoms.
Found on 
http://thinkexist.com/dictionary/meaning/whiten/
 Whit'en  intransitive verb
Whit'en  intransitive verb [ 
 imperfect & past participle   Whitened ; 
 present participle & verbal noun   Whitening .] [ Middle English 
 whitenen ; confer Icelandic 
 hvītna .] To grow white; to turn or become white or whiter;...
Found on 
http://www.encyclo.co.uk/webster/W/34
 Whit'en  transitive verb
Whit'en  transitive verb  To make white; to bleach; to blanch; to whitewash; as, to 
 whiten a wall; to 
 whiten cloth. « The broad stream of the Foyle then 
 whitened by vast flocks of wild swans.» 
 Macaulay.  Syn. -- See 
 Blanch . 
Found on 
http://www.encyclo.co.uk/webster/W/34

[
v] - turn white
Found on 
http://www.webdictionary.co.uk/definition.php?query=whiten
  No exact match found.