an vs through

an

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

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

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. 

num
  • one 

through

prep
  • To (or up to) and including, with all intermediate values. 

  • Entering, then later leaving. 

  • From one side of an opening to the other. 

  • By means of. 

  • In consequence of; as a result of. 

  • Surrounded by (while moving). 

adj
  • Passing from one side of something to the other. 

  • Without a future; done for. 

  • No longer interested; wearied or turned off by experience. 

  • Proceeding from origin to destination without delay due to change of equipment. 

  • In possession of the ball beyond the last line of defence but not necessarily the goalkeeper; through on goal. 

  • Finished; complete. 

noun
  • A large slab of stone laid in a dry-stone wall from one side to the other; a perpend. 

postp
  • From beginning to end. 

adv
  • Completely. 

  • Out into the open. 

  • During a period of time; throughout 

  • From one side to the other by way of the interior. 

  • From one end to the other. 

  • To the end. 

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