"oblitesco" - L. to conceal oneself
"oblittero" - L. to cancel , blot out
Removes traces or tracks left by someone.
"oblivisci" L. forget
Modifies or erases portions of a person's memory.
Bertha Jorkins had had a Memory Charm placed on her by Crouch Sr. after she discovered Barty Crouch Jr. at the Crouch home (GF33). Voldemort broke through it, but the process left her mind damaged and he killed her (GF1).
Mr. Roberts, the campground manager near the Quidditch World Cup, needed ten Memory Charms a day or he started noticing odd things going on. Later, after he and his family had been attacked by the Death Eaters, they all received Memory Charms (GF7, GF9).
Lockhart used Memory Charms on those whose adventures he claimed as his own. He'd interview someone who battled some creature or conquered some dark foe, then write the story as if he did it himself and cast a Memory Charm on to the person so they'd forget it was really them. He tried to do the same to Harry and Ron, but it backfired onto him instead (CS16).
The Ministry of Magic arranged for the President of an unnamed country to forget to telephone the Muggle Prime Minister in order to clear time on the latter's schedule for an interview with Cornelius Fudge and Rufus Scrimgeour (HBP1).
A Ministry wizard whose job it is to cast Memory Charms is called an Obliviator (GF7).
Hermione modified her parents' memories, making them forget not only who they were and that they had a daughter, but making them think that they had different names and wanted to move to Australia (DH6). However, she later said that she had never cast a Memory Charm before (DH9).
- Hermione looked as though she had been Obliviated when she recalled seeing the locket Horcrux two years before (DH10).
"obscuro" L. to cover, darken, obscure
Blocks someone's vision.
Hermione used this spell to create a blindfold on the painting of Phineas Nigellus Black (OP15).
"occlusum" - L. to block or close + "mens" - L. mind
Specialized branch of magic, not usually taught at Hogwarts, which consists of protecting one's mind against outside intrusion.
See also LEGILIMENS.
"oppugno" L. to attack, assault
Causes conjured creatures under the control of the caster to attack the target.
"Orchideae" L. name for the orchid plant family
Conjures a bouquet of flowers out of the end of a wand.
See CONJURING SPELLS.