An upgrade is an improvement. This word has gained popularity in recent years when a business or an individual wants to improve something that exists. The word "upgrade" also refers to a better offer for a customer:
The hotel offered us an upgrade on our hotel room.
The airline offered us an upgrade on a flight to New York.
An upgrade is available if we want to rent a car that’s a little nicer.
A free upgrade is available for this computer program.
Check to see what kinds of upgrades there are.
This word is often used as a verb:
Todd really needs to upgrade his wardrobe. (His clothes are old; he needs new clothes.)
You should upgrade your computer’s operating system to something that’s newer.
The furniture in the office needs to be upgraded.
Would you like to upgrade your reservation?
We upgraded to first class. (This happens on a flight.)
Many people have noticed that Ron is upgrading his wardrobe.