indentation vs indenture

indentation

noun
  • The act of indenting or state of being indented. 

  • The act of beginning a line or series of lines at a little distance within the flush line of the column or page, as in the common way of beginning the first line of a paragraph. 

  • A measure of the distance from the flush line. 

  • A notch or recess, in the margin or border of anything. 

  • A division unit of a piece of law distinguished by its indentation or by a dash. 

  • A recess or sharp depression in any surface. 

indenture

noun
  • An indentation; a recess. 

  • A contract which binds a person to work for another, under specified conditions, for a specified time (often as an apprentice). 

  • A document, written as duplicates separated by indentations, specifying such a contract. 

verb
  • To indent; to make hollows, notches, or wrinkles in; to furrow. 

  • To bind a person under such a contract. 

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