Pern Lexicon
Need to know some of the terms of Pern? Well this is where you'll find some of them.

Agenothree: a common chemical on Pern, used in the flamethrowers. HNO3
Between: an area of nothingness and senspry deprivation between here and there.
Black rock: nalogous to coal.
Day Sisters: a trio of stars visible from Pern.
Dawn Sisters: an alternate name for Day Sisters.
Deadglow: a numbskull, stupid. Derived from glow.
Fellis: a flowering tree.
Fellis juice: a juice made from the fruits of the fellis tree; a soporific.
Fire-stone: phosphine-bearing mineral, which dragons chew to produce flame.
Glow: a light-source which can be carried in a hand-basket.
High Reaches: mountains on the northern continent of Pern.
Hold: a place where the common people live; originally they were cut into mountains and hillsides.
Impression: the joining of minds of a dragon and his rider-to-be at the moment of the dragon's hatching.
Interval: the period of time between passes, generally 200 years.
Klah: a hot stimulating drink made of tree bark and tasting faintly of cinnamon.
Looks to: is Impressed by.
Long Interval: a period of time, generally twice the length of an interval, in which no Thread falls and Dragonmen decrease in number. The last Long Interval is thought the herald the end of Threads.
Month: four sevendays.
Numbweed: a medicinal cream which, when smeared on wounds, kills all feeling; used as an anaesthetic.
Oldtimer: a member of one of the five Weyrs which Lessa brought forward four hundred Turns in time. Used as a derogative term to reffer one who has moved to Southern Weyr.
Pass: a period of time during which the Red Star is close enough to drop Thread on Pern.
Pern: third star of the star Rukbat's five planets. It has two natural satelites.
Red Star (sic): Pern's stepsister planet. It has an erratic orbit.
Rukbat: a yellow star in the Sagittarian Sector, Rukbat has five planets and two asteroid belts.
Sevenday: the equivalent of a week on Pern.
Thread: (mycorrhizoid) spores from the Red Star, which descend on Pern and burrow into it, devouring all organic material they encounter.
Turn: a Pernese year.
Watch-wher: a nocturnal reptile distantly related to dragonkind.
Weyr: a home of dragons and their riders.
weyr: a dragon's den.
Weyrsinger: the Harper for the dragonriders, usually also a dragonrider.
Wherries: a type of fowl roughly resembling the domestic turkey of Earth, but about the size of an ostrich.
Withies: water plants resembling the reeds of Earth.

*Courtesy of Merangue