an vs opposite

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. 

num
  • one 

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

opposite

prep
  • In a complementary role to. 

  • Facing, or across from. 

  • On another channel at the same time. 

adv
  • In an opposite position. 

adj
  • Facing in the other direction. 

  • Of leaves and flowers, positioned directly across from each other on a stem. 

  • Located directly across from something else, or from each other. 

  • Of either of two complementary or mutually exclusive things. 

  • Extremely different; inconsistent; contrary; repugnant; antagonistic. 

noun
  • Something opposite or contrary to something else. 

  • An opponent. 

  • A person or thing that is entirely different from or the reverse of someone or something else; used to show contrast between two people or two things. 

  • An antonym. 

  • An additive inverse. 

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