number one vs oneth

number one

noun
  • Used other than figuratively or idiomatically: see number, one. 

  • The main goalkeeper of a team, so-called because they wear the number 1 on the back of their kit. 

  • The most important person, the one who is in charge. 

  • Urine; urination. 

  • A large town where theatrical performances may expect to achieve success. 

  • Oneself, being considered foremost, as by an egoist. 

  • Someone who is top of a ranking, who is ranked first. 

  • The batsman who opens the batting. 

  • The single that has sold the most in a given period. 

  • A first lieutenant. 

adj
  • First; foremost; best, often used after its headword. 

oneth

noun
  • An ordinal value that is represented by an expression ending in 1 such as the (n + 1)th. 

  • A fractional part of an integer ending in one 

adj
  • 'first', or other ordinal derivatives of 'one', such as hundred-and-oneth or minus-oneth 

  • Used at the end of algebraic expressions indicating ordinal position that end in 1, such as (k+1)ᵗʰ 

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