Coarse and unrefined, crude.
Resembling dirt or soil (i.e. earth).
Like or resembling the earth or of the earth.
Covered with earth (mud, dirt).
Down-to-earth, not artificial, natural.
Not noble; ignoble; base.
Of a metal, being at the lower end of the electrochemical series, i.e. oxidising readily.
To make (someone or something) no longer noble