Cant is a term used to describe a form of slang or jargon, this term was in popular use in the late 19th and early 20th centuries.
Planescape is a series of novels, an RPG and a computer game. It deals with the Multiverse and as such needs to coin lots of terms to describe some rather estoric stuff. In addition lots of not-so-philisophical slang was introduced in the Planescape boxed set and has constantly grown, spread mainly accross the internet. The following is a selection of Planescape Cant terms, hundreds more can be found elsewhere on the net. Feel free to add your own.
The More Technical Cant:
Layer: A Plane that is part of a group of linked Planes of a similar nature, for example The Seven Heavens is made up of Seven Layers.
Realm: A loose term which can refer to the following
A stable area in a Void (such as the Demi-Planes in the Ethereal Plane)
Areas where voids overlap other Planes (such as the Border Ethereal)
The areas on the Outer Planes which are under the direct control of a Power.
Demi-Plane: A small 'island' world in the Ethereal Plane which is based around a theme or concept.
Planar: 1: A person/creature who is part of the Planewalking culture, 2: Of the Planes
Planewalker: A person who often planeshifts
Planerunner: A Planewalker adventurer.
Planeshift/'Shift: To intentionally move to another plane
Planedump: To be moved to another plane without wanting to go there (you can Planedump someone who is then considered Planedumped).
Outer Planes/Great Wheel: The planes of alignment, each based around a moral or ethic, this includes the Outlands
Inner Planes: The Ethereal, The Elemental and the Prime Planes
Prime/Prime Material: The plane of infinite layers and most campaigns, the one you are on now.
The Outlands: The Plane of the Balance
Factions: Interplanar organisations based around philosophies.
The Great Voids: The Ethereal Plane and the Astral Plane
The Less Technical Terms
Bar That: Shut up
Barmy: Someone sent insane by the immensity of the Planes, or just plain nuts
Berk: Taken from contempory British slang. Fool/someone who should know better.
Blood: Expert who has achieved a lot. Calling someone a Blood is a mark of high respect for their capabilities.
Bob: Cheat, rob or mislead
Bod/Body: A corporal person who is not a Power. A broad term basically meaning anyone with a body.
Bone-Box: A berks head. As in "Stop rattling your bone box berk"="Please cease your chatter young scamp"
Bubber: A drunk
Chiv: Bladed weapon
Cony-Catcher: Thief or con-man. Someone who bobs berks
Cross Trade: Anything to do with the black market.
The Chant: Any useful information about facts, moods or events.
Cutter: Someone who is resourceful and daring
Clueless: Someone who does not understand basic planar politics ("So the Devas don't get on with the Tanar'ri then?") or how to survive in the planes ("So, you mean I should bring some sunblock to this Athas place, right?").
Dark: Secret or unknown
Dead Book: The book of Charon. Anyone "In the Dead Book" is now a Petitioner. Someone who "Cheats the Dead Book" is some form of undead, or very lucky.
High-up: Powerful eg. "He's a high up in the government" or "That was a sodding high up fireball!"
Hipp: To Hipp is to Planedump someone; to strand someone on a Plane. Such a person is then considered Hipped
Kip: Area deemed safe enough to have a nights sleep in. Often used to describe a cheap rented room.
Path: Some form of interplanar travel that requires actual physical movement to 'shift.
Peel: Swindle, con or trick
Prime: Either the Prime Material Plane or someone from that Plane
Pike off: As in "Pike off Leatherhead" or "You shouldn't have said that, now he's really Piked Off!"
Rube: Someone who is easily fooled
Scan: Look/Listen/Learn as in "Scan this berk" or "You Scan?"
Scragged: Nabbed/nicked/taken/stolen/killed as in "I scragged the jewels as we walked out$quot; or "I scragged him with a fireball!"
Sod: Derived from contempory British slang. Can be used as follows:
1: Someone who is so useless they should be pitted. eg. "You sod!"
2: A generic unpleasant action used in a derogatory fasion as in "Sod it!" or "Sod off you sod!"
Sodding: A derogatory term used to express magnitude as in "Sod off you sodding sod!"
Spellslinger: Anyone who uses some form of magic
Tech: Any technology as advanced as crossbows upwards. Often seen as just another form of magic
Tumble to: Realise, as in "He'll tumble to it sooner or later."