Palp semaphore language: The spiders' language of gesture and vibration, made with the palps and backed by stamping feet, and the main way Portia's people talk.
Peer group: A peer group is the base social unit of the spider cities. Spiderlings that hatch in the same crèche band together as juveniles and keep the bond as adults. The larger groups hold a peer house, a complex of silk walled chambers.
Temple: The worship of the Messenger among the spiders of the green world, with its temples, priestesses and doctrine. Its priests treat the mathematical signal from the sky as the word of God, and the old guard forbids any attempt to answer it.
The mutiny: Colonists aboard the ark ship Gilgamesh refuse to be left on a moon without an atmosphere, seize the armoury and take Holsten Mason and Isa Lain hostage. They steal a shuttle for the green planet, where the satellite destroys it and most of them die.
The plague: An epidemic virus that swept the spider cities of the green planet and killed hundreds of thousands before it reached Great Nest. The city survived on a serum made from immune spiderlings and the nanovirus.
Understanding: Knowledge that the nanovirus writes into a spider's body and passes to its offspring, at first inherited at birth and later traded, distilled and drunk.
Uplift: Uplift is Doctor Avrana Kern's project to raise another species to intelligence on Kern's World with an engineered virus, in two phases. The monkeys it was built for burned before it began, and the virus raised the arthropods instead.