umber vs umbrel

umber

noun
  • A grayling. 

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

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

verb
  • To give a reddish-brown colour to. 

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

umbrel

noun
  • An umbrere; the visor of a helmet 

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