Several new words or created words come up in Harry Potter in the world the J.K. Rowling has created.
This was pretty straightforward as it is used to refer to characters such as the Dursleys it is obvious that it means non-magical beings
While it is early on established that this is the Wizarding school other things tell a reader that this is an important place. There is a seal on the envelope sent to Harry. Also the school has its own train.
Ok so this is the name of a person but it is a very important one. I quickly found out through how shocked people are that Harry says it and that until a certain point Harry only know of him as He-who-must-not-be-Named that he is the antagonist.
It is first established when Harry meets Hagrid that Gringotts is the Wizarding bank. However, it's reputation is further explored in the book. They have dragons that guard the vaults. They have a special cart that takes you to your vaults. Also the reaction that is received when they get broken into tells you that it is not easy to break into the bank.
5. Berty Botts Every Flavor Beans
This candy is established as one as soon as Harry sees it on the trolley on the Hogwarts Express. They appear to be similar to jelly beans, but have an aspect that each color may be a different flavor. It could be good or bad it's like a game.
6. The Sorcerer's Stone
You first come across this on a Chocolate frog card and its connection to Dumbledore. The package Harry and Hagrid pick up at Gringotts holds this. You find out that it can make metal into gold and makes the Elixir of Life.
7. The Sorting Hat
The first allusion to it happens when McGongall says something about a test to get put into the four houses. Then you see it placed on a stool. You find out that it has a consciousness of some sort or at least is given one by enchantment. You learn that it can be persuaded because Harry convinces it to put him in any house but Slytherin.