a quantity much larger than is needed
"The factory produced such a surplus of widgets that they had to store thousands in their warehouse."
That which remains when use or need is satisfied, or when a limit is reached; excess; overplus.
"The factory donated all its surplus clothing to charity once their inventory met the monthly demand."
In plain English: Surplus is any amount left over after you have used what you needed.
"The farmers donated their surplus crops to feed the local shelter."
Usage: Use "surplus" to describe an amount that exceeds what is needed or allowed. It often refers specifically to excess inventory, funds remaining after expenses, or people dismissed because they are no longer required by the employer.
To treat as surplus to requirements; to sell off or dismiss from employment, etc.
"The factory manager decided that three of the older machines were surplus and ordered them sold at auction."
In plain English: To surplus something means to have more of it than you need, so that the extra amount is left over.
"The company hopes to surplus its inventory by selling items online at steep discounts before they expire."
more than is needed, desired, or required
"trying to lose excess weight"
"found some extra change lying on the dresser"
"yet another book on heraldry might be thought redundant"
"skills made redundant by technological advance"
"sleeping in the spare room"
"supernumerary ornamentation"
"it was supererogatory of her to gloat"
"delete superfluous (or unnecessary) words"
"extra ribs as well as other supernumerary internal parts"
"surplus cheese distributed to the needy"
Being or constituting a surplus; more than sufficient
"The garden produced such an abundant harvest that there was plenty of food in surplus to feed our neighbors."
In plain English: Surplus means having more of something than you need to get by.
"The surplus inventory was sold off at a discount to clear space on the shelves."
The word entered English directly from Middle French as surplus, where it originally meant an excess or overabundance that remained after a deduction had been made. It traveled into our language during the medieval period without undergoing significant changes to its core meaning of something left over.