em vs u

em

noun
  • The name of the Latin-script letter M. 

  • A unit of measurement equal to the height of the type in use. 

  • The name of the Cyrillic script letter М / м. 

intj
  • a form of hesitant speech, or an expression of uncertainty; um; umm; erm 

pron
  • A gender-neutral third-person singular object pronoun, the objective case of ey, equivalent to the singular them and coordinate with him and her. 

u

noun
  • The name of the Latin-script letter U/u. 

  • A thing in the shape of the letter U 

character
  • The twenty-first letter of the English alphabet, called u and written in the Latin script. 

pron
  • you (in text messaging and internet conversations) 

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