"Pointing his wand at nothing in particular, he gave it an upward flick and said Levicorpus! inside his head... There was a flash of light... Ron was dangling upside down in midair as though an invisible hook had hoisted him up by the ankle."
The incantation can be divided into two separate Latin words; levare means "lift", and corpus is translated to "body". It could also be translated as "Light Body".
Behind the scenes
The effect of this spell may be a reference to the Hanged Man, a Tarot card that depicts a saint-like figure being hung upside down from his ankle.
In Harry Potter and the Order of the Phoenix (film), this is a verbal spell taught to Dumbledore's Army; it is used to lift people in this medium, but not by the ankle, as the victim's of the spell are seen being levitated onto the air as long as the user concentrates, as loss of concentration causes the spell to break immediately and the victim to fall to the ground. This was shown when Cho Chang was distractedly looking at Harry while Nigel, who she was levitating, suddenly fell to the floor. However, when Luna Lovegood uses it on a Death Eater in the Ministry of Magic, it sends the Death Eater flying upwards, similarly to Alarte Ascendare, except that the victim does not come back down, suggesting it does suspend him in the air or to the ceiling.
Also in the film, James Potter levitated Severus off the ground with Impediment Jinx instead of Levicorpus, though Severus still was dangled upside-down.
↑In Harry Potter and the Half-Blood Prince, Hermione noted "We've seen a whole bunch of people use it, in case you've forgotten. Dangling people in the air. Making them float along, asleep, helpless." Harry stared at her. With a sinking feeling, he too remembered the behaviour of the Death Eaters at the Quidditch World Cup.