an vs mid

an

prep
  • In each; to or for each; per. 

article
  • Used before one and words with initial u, eu. 

  • Used before a vowel sound. 

  • Used before all consonants. 

  • Used before /h/ in an unstressed syllable. 

  • Used before /h/ in a stressed syllable. 

noun
  • The first letter of the Georgian alphabet, ა (Mkhedruli), Ⴀ (Asomtavruli) or ⴀ (Nuskhuri). 

num
  • one 

mid

prep
  • With. 

  • Amid. 

noun
  • A mid-range. 

adj
  • Made with a somewhat elevated position of some certain part of the tongue, in relation to the palate; midway between the high and the low; said of certain vowel sounds, such as, [e o ɛ ɔ]. 

  • Trashy; low-quality. 

  • Denoting the middle part. 

  • Of mediocre quality. 

  • Of marijuana, midgrade. 

  • Occupying a middle position; middle. 

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