* Half-Blood: This refers to the fact that Snape's father was a Muggle (non-magical) and his mother was a witch.
* Prince: This was a title that Snape acquired during his time at Hogwarts. He was an exceptionally talented student who excelled in Potions, often writing in his textbook, which was later discovered by Harry Potter. This book, filled with Snape's notes, was referred to as the "Half-Blood Prince's" book.
It's important to note: Snape didn't actually use the title "Half-Blood Prince" himself. It was a nickname given to him by other students due to his prowess in Potions and his unusual family background.