brownify vs umber

brownify

verb
  • To make or become more brown. 

  • To cause to contain more racially 'brown' people, elements, or culture. 

  • To become brown due to increased levels of humic material. 

umber

verb
  • To give a reddish-brown colour to. 

adj
  • Of a reddish brown colour, like that of the pigment. 

noun
  • A dusky brown African wading bird (Scopus umbretta) allied to the shoebill and herons; a hamerkop. 

  • A grayling. 

  • A brown clay, somewhat darker than ochre, which contains iron and manganese oxides. 

How often have the words brownify and umber occurred in a corpus of books? (source: Google Ngram Viewer )