"Merlins beard ...this is some map. Potter!"
-- Fake Moody/Barty Crouch Jr. (GF25)
Effect: tracks the movements of anyone within a certain area through the use of dots on a parchment.
References from the canon
- The Marauder's Map uses the Homonculus Charm to show the location of every being at Hogwarts (Pm)
- The charm identifies the true identity of the person whether they are disguised as an Animagi, hiding under the Cloak of Invisibility, or changed by Polyjuice Potion (PA17,PA18,GF25). However it does not distinguish between generations if people have the same name: "Bartemius Crouch" appeared on the Marauder's Map in Snape's Office and Harry couldn't tell if it was the senior or junior.
- Peeves the Poltergeist, Mrs. Norris the cat (kneazle), and the Hogwarts Ghosts all showed up on the Marauder's Map thanks to the Homonculus Charm (GF25,Pm).
"Homonculus" seems to be a variation of the Latin homunculus (plural homunculi), literally "little person" or "tiny human artificially produced"