Password

Passwords are used throughout Hogwarts Castle to restrict entry to certain areas. The inspirations for these passwords come from specific events and experiences throughout the storyline. Passwords appear to change on a frequent basis.

During Sir Cadogan's period of guarding the Gryffindor common room, he changed passwords so frequently that Neville Longbottom had to write them down. This list was snatched by Crookshanks and was given to Sirius Black/Padfoot, allowing him entrance.

Gryffindor common room

 * abstinence
 * balderdash
 * banana fritters
 * baubles
 * caput draconis
 * dilligrout
 * fairy lights
 * flibbertigibbet
 * fortuna major
 * Mimbulus mimbletonia
 * oddsbodikins
 * pig snout
 * quid agis
 * scurvy cur
 * tapeworm
 * wattlebird

Ravenclaw Tower
(Instead of a password, a conundrum is posed.)

Slytherin Common room

 * pure-blood

Headmaster's Office

 * Acid Pops
 * Cockroach Clusters
 * Fizzing Whizbee
 * sherbet lemon (UK) / lemon drop (US)
 * Toffee Eclairs
 * Dumbledore

Prefects' Bathroom

 * pine fresh

One-Eyed Witch Passageway

 * Dissendium

Chamber of Secrets

 * "Open up" (spoken in Parseltongue)

Potterwatch

 * Albus
 * Mad-Eye