What part of speech is “in”?

In is primarily classed as a preposition, but it can be classed as various other parts of speech, depending on how it is used:

  • Preposition (e.g., “in the field”)
  • Noun (e.g., “I have an in with that company”)
  • Adjective (e.g., “Tim is part of the in crowd”)
  • Adverb (e.g., “Will you be in this evening?”)