/ ɪkˈspaʊnd; NAmE / verb
expound sth (to sb) | expound on sth ( formal ) to explain sth by talking about it in detail :
[ vn ]
He expounded his views on the subject to me at great length.
[ v ]
We listened as she expounded on the government's new policies.
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WORD ORIGIN
Middle English expoune (in the sense explain (what is difficult) ): from Old French espon- , present tense stem of espondre , from Latin exponere expose, publish, explain, from ex- out + ponere put. The origin of the final -d (recorded from the Middle English period) is uncertain (compare with compound , propound ).