What is a poem with fourteen lines and a mixed rhyme scheme?

A poem with fourteen lines and a mixed rhyme scheme is most likely a sonnet, particularly a variant of the traditional sonnet forms. There are three main types of sonnets, each with its corresponding rhyme scheme: 

 

  • The Petrarchan or Italian sonnet (ABBA ABBA CDE CDE or ABBA ABBA CDC DCD)
  • The Shakespearean or English sonnet (ABAB CDCD EFEF GG)
  • The Spenserian sonnet (ABAB BCBC CDCD EE)

 

There are also modern or contemporary sonnets that often experiment with various rhyme schemes or may even use slant rhymes or no rhyme at all.