baronet
A British noble title passed from father to eldest son.
A baronet is a hereditary title in Britain, ranking below a baron but above a knight. When a man becomes a baronet, he can put “Sir” before his name, just like a knight, but unlike a knight, he can pass the title down to his son. So if Sir Robert is a baronet, his eldest son will become the next Sir Robert (or whatever his name is) after his father dies.
The title was created by King James I in 1611 as a way to raise money. Men who wanted to become baronets paid the king, and in return, they received this hereditary honor. A baronet gets to use the letters “Bt” or “Bart” after his name, so you might see “Sir Thomas Browne, Bt” in a book.
You'll encounter baronets often in British novels and historical stories. In Jane Austen's Persuasion, Sir Walter Elliot is a vain baronet who cares more about his title than anything else. The title matters socially but doesn't come with political power or a seat in the House of Lords the way higher titles like baron or earl do.
Think of it as a lesser form of nobility, valuable for prestige but not actual governing authority.