Ark of Fools: Lexicon

Ageless: "native" inhabitant of the Skin
Airwards: local "north" in the Interior
Akadazia: local name of the demi-plane in the Interior.
Anniversary: "New year's day" as defined in Face
the Ark: nickname for the body of Armaz-Daka (the dead god) (including the Interior)
Armaz: the good-aligned half of the dead god.
Astral year: 360 days, 12 months of 30 days, 5 weeks of 6 days
Barefoot priest: a Dirtside priest not affiliated with any temple, often a mendicant.
Country cleric: similar to a "barefoot priest", except they tend to be less nomadic, and somewhat wealthier.
Daka: the evil-aligned half of the dead god.
Dirtsider: vulgar Skinside term for an inhabitant of the Interior.
Earthwards: local "west" in the Interior
Ephemeral: any mortal non-astral dweller. Used mainly to refer to Akadazians (natives of the Interior.)
Exile: anyone from some other plane who ended up on the Ark.
Firewards: local "south" in the Interior
Glieth-berry: local plant, not found anywhere else in the planes. Revered by local druids as a holy plant. Edible berries. Tart. Glieth-berries are small, shaped and colored like drops of blood --- green when new, bright red when ripe, dark red when fermenting. Skin smooth when new, wrinkled when fermenting. They grow on thorny bushes that like to grow on the edge between forest and meadow, in temperate zones.
Graymorning oak: local type of oak, found in the eastern mountains, adapted to the watery conditions there.
Into the Silver: going into the true astral plane from the Skin.
Local year: Akadazian year, varies from about 6 astral months to 2 astral years.
the Pit: alternative name for the Underskin (the hollowed out true physical interior of the dead god, as opposed to the demiplane Akadazia.)
Silver Key: the emblem of the Ancient and his Sworn. Also an actual magical item. Used in any other plane, it transports up to 8 people back to the astral plane, similar to the plane shift spell. It is physically shaped like a large silver key (the type that looks like a rod with things sticking out).
Skinsider, Skinny: anyone on the Ark not living in Akadazia.
Waterwards: local "east" in the Interior

Acknowledgements: Thanks to the players, especially Marisella, for adding to this list!