'in writing' definitions:

Definition of 'in writing'

From: WordNet
adverb
As written or printed; "this is exactly what the composer had set down on paper" [syn: on paper, in writing]
adjective
Written or drawn or engraved; "graphic symbols" [syn: graphic, graphical, in writing(p)]

Synonyms of 'in writing'

From: Moby Thesaurus