The word “of” is a preposition.

Quick Scoop: What part of speech is “of”?

In modern English grammar, “of” is classified as a preposition because it shows relationships between words in a sentence, often about belonging, origin, part–whole, or other kinds of connection.

What “of” does in a sentence

Common relationships “of” expresses:

  • Possession or belonging: “the plays of Shakespeare,” “a friend of mine.”
  • Part of a whole: “a piece of cake,” “a cup of coffee.”
  • Origin or source: “a man of humble origins,” “a fish of the western Atlantic.”
  • Description or quality: “full of joy,” “capable of great kindness.”
  • Topic or reference: “stories of her travels,” “the cost of the repairs.”

In all these, “of” links a noun (or noun phrase) to another word and shows how they are related, which is exactly what prepositions do.

A few quick examples

  • “The courage of the young woman inspired us.”
  • “He is a student of the university.”
  • “She’s a friend of my mother’s.”

In each sentence, “of” introduces a phrase that explains whose, what kind, or which one, reinforcing its role as a preposition.

TL;DR: If you’re wondering “what part of speech is of?” — it’s a preposition.

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