India, Nov. 8 -- Gryffindor, butterbeer, chocolate frog. scores of terms have crept from the Harry Potter books into the English language. Some are bywords for a state of mind; others for a personality type. Muggle and Quidditch are even in the dictionary. Here are some of our favourites. l The sorting hat and the four houses: One of the remarkable things about the world of the Potter books is that there is room here for everyone. At Hogwarts, personalities are accommodated, rather than flattened to force-fit a template. It is understood that while Gryffindor is believed to hold students who are brave and loyal, they can also be reckless and suffer from a saviour complex. And while members of Slytherin are ambitious, calculating and cunning, they have good in them too. Hufflepuffs, similarly, are largely loyal, dependable and unpretentious. Ravenclaws are intellectual, curious and academically inclined. Fans have been sorting themselves into these houses since 1997. l Wrock: Wizard rock or wrock is a musical sub-genre that does not feature in the books, but has evolved as a sort of tribute to them, since the early Aughts. Leading bands include Harry and the Potters from Massachusetts, and Draco and the Malfoys from Rhode Island. They perform mainly at fan events. l Butterbeer: This frothy drink has, for generations of readers, come to signify a specific golden period of adolescences: that time of early joyful freedom, without care. Introduced in the third book, .Prisoner of Azkaban (1999), it has filtered into dessert cafe menus around the world. Recipes typically feature cream soda, whipped cream, butterscotch. l Dementor: These tall, shadowy, humanoid figures guard the Prison of Azkaban, in the wizarding world. They spread despair, drain away joy and vitality, revive trauma. They have become a way to talk about the burdens of anxiety, depression, ennui. l Patronus: The spell it takes to summon a Patronus requires grit, willpower, and a lifetime of happy memories. But cast it right, and the result is a silvery holographic spirit animal that spreads a protective shield around the spell-caster that can ward off even dementors. Harry's Patronus, a silvery stag, saves him over and over. Isn't that a remarkable idea: Live well, and when the going gets tough, a quiet force of hope and joy will turn up to help. Our world has them, of course: friends, parents, siblings, coworkers....