Dissendium

Dissendium (dis-EN-dee-um) is a spell that opens the secret passageway behind the statue of the Humpbacked Witch in Hogwarts straight into the cellar of Honeydukes in Hogsmeade.

Known practitioners

 * Fred Weasley
 * George Weasley
 * Harry Potter
 * Hermione Granger

Etymology

 * 'Dissendium' seems to have the same roots as 'Dissemble' so dissendium might mean to part as the one eyed witch's hump parted from the rest of her body.
 * Quite simply, a phonetic spelling of the English word "descend" with a common Latin noun ending attached (-ium). The name also vaguely suggests "dissident", meaning to be against the laws. It could also come from the Latin word Dissocio, which means to part or to separate (in its verb form). The word en can mean both here and look Dium, could refer to the sun and normally translates as day or, more appropriately, today but can also be used as the command now. Together Dissendium could mean Separate here, now.

Behind the scenes

 * This may not be a spell in the strict sense, but a magical password like "Mimbulus Mimbletonia" (once a password for the Fat Lady) and "Acid Pops" (one of the passwords for Dumbledore's office gargoyle in 1996). However, it is mentioned that Harry has to tap the statue of the crone while saying the spell in order for it to open up. Also, the name of the spell is similar to the way other spells are named, suggesting that it may be a spell in its own right. A more logical explanation would be that it opens secret passages in general, although it is only used on the particular statue in the series, so this is not confirmed, it is just an idea.
 * In the first part of the film adaptation of Harry Potter and the Deathly Hallows, Harry Potter casts the spell 'Dissendium' in an attempt to destroy Slytherin's locket. So, we can suppose that 'Dissendium' is actually a real spell or a film mistake. The spell, however, had no effect, since Horcruxes can't be destroyed by simple spells. It's odd that the first time the spell is used in the films is for a different purpose. It's possible that he was simply attempting to open it.

Appearances

 * Harry Potter and the Prisoner of Azkaban
 * Harry Potter and the Deathly Hallows: Part 1
 * Lego Harry Potter: Years 1-4

Dissendium Halkhios