I would like to ask when we should use prepositions such as "on", "upon" or "about" with the word expound. In dictionaries there are examples showing both usage but I cannot figure out in which conditions I should prefer one to another. Can we say it is optional?

She expounded her theory further in the course of her talk.

We listened as she expounded on the government's new policies.

3 Answers 3


Expound means to set forth, declare, state in detail (doctrines, ideas, principles; formerly, with wider application); To explain, interpret (what is difficult or obscure) (OED). The verb is not used with 'on', 'upon' or 'about'.

For example,

"Our author proceeds to expound his own analysis."

"The doctrines expounded by St. Augustine."

  • Thank you for the answer but I have seen many usage with prepositions. corpus.byu.edu/coca
    – Mrt
    Dec 11, 2016 at 0:21
  • But you can also expound on/upon Plato's Republic. I've never heard of expounding about, though.
    – WS2
    Dec 11, 2016 at 0:22
  • @Mrt - yes, so have I (including your Oxford dictionaries link, noting too that they don't provide an example). Historically (i.e. according to the online OED) it appears that expound on/upon was not used. To take WS2 example, a classics scholar expounds Plato's Republic. The fact that I could easily insert 'on/upon' after 'expounds' doesn't make it right, it just means that nowadays some people feel the word needs prepositional support!
    – Dan
    Dec 11, 2016 at 0:33
  • Me too. Clearly both versions are possible. Consider this - books.google.com/ngrams/…
    – Dan
    Dec 11, 2016 at 0:35
  • 1
    @Dan I would tend to agree with that. The modern prepositional support is absent from the OED, but I do think it is so widespread in everyday use that the point has been reached where it should be included.
    – WS2
    Dec 11, 2016 at 10:28

Here's what dictionary.com says:

verb (used with object)

  1. to set forth or state in detail: to expound theories.

  2. to explain; interpret.

verb (used without object)

  1. to make a detailed statement (often followed by on).

Upon is equivalent to on, and it sounds so nice and pompous, just like expound. You may certainly say "expound upon"!

About wouldn't be a good choice.

  • ... at the risk of making a good word ridiculous!
    – Dan
    Dec 11, 2016 at 19:46

The use of "expounded" with prepositions such as on, upon, or about is not historically common. The combination of "expounded" and "unto" was much more common. Here are some examples of the use of "expounded" from the King James Bible:

"And the Spirit of the Lord came upon him, and he went down to Ashkelon, and slew thirty men of them, and took their spoil, and gave change of garments unto them which expounded the riddle. And his anger was kindled, and he went up to his father's house." - Judges 14:19

"But without a parable spake he not unto them: and when they were alone, he expounded all things to his disciples." - Mark 4:34

"And beginning at Moses and all the prophets, he expounded unto them in all the scriptures the things concerning himself." - Luke 24:27

"And he began to speak boldly in the synagogue: whom when Aquila and Priscilla had heard, they took him unto them, and expounded unto him the way of God more perfectly." - Acts 18:26

"And when they had appointed him a day, there came many to him into his lodging; to whom he expounded and testified the kingdom of God, persuading them concerning Jesus, both out of the law of Moses, and out of the prophets, from morning till evening." - Acts 28:23

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