Here is a list of terms commonly used in the Dragon Books and their meanings. If there's one in particular you're looking for, go to EDIT on your toolbar, then go to FIND and type in the word you're after.
Agenothree: a common acid-like chemical on Pern. Groundcrews use it during a fall.
Apprentice: The lowest level in a Crafthall, basically a trainee.
Bahrain: The smallest of the three ships which brought people to Pern, captained by Jim Tillek.
Belior: Pern's larger moon.
Between: an empty space of sensory deprivation where dragons go to get from one place and another.
Buenos Aires:Another of the three colony ships, captained by Ezra Keroon.
Craftmaster: The highest level in a crafthall, a fully trained craftsman.
Day Sisters: three 'stars' visible on Pern's horizon at dawn and dusk, which are actually the ships that brought the settlers to Pern.
Dawn Sisters: another name for the Day Sisters
Deadglow: an insult. Basically, it means 'fool'.
Fellis: a flowering tree native to Pern.
Fellis juice: made from the fruits of the fellis tree, it is a powerful sopoforic.
Fire lizard: A smaller version of the dragon native to Pern.
Firestone: phosphine-bearing rocks which dragons chew to produce a flame.
Glow: a light source which can be carried in a handbasket.
Harper: Harpers are responsible for the education of children in hold, hall and weyr. They are the musicians and entertainers of Pern and may also be called upon to arbitrate disputes.
Headwoman: someone selected by the Weyrwoman to take charge of the domestic duties in a weyr: cleaning, cooking, childcare, etc.
High Reaches: the mountains in the north of the Northern Continent.
Hold: A dwelling cut out of rock so it is safe from Thread. Where common people live.
Holdless: people who have no hold for whatever reason, often because of crime.
Impression: the joining of minds between a dragon and their rider at Hatching.
Interval: the time between passes of the Red Star, usually about 200 Turns.
Journeyman: The middle level in a crafthall. An apprentice who has reached a certain level of competence and 'journeys' around Pern.
Klah: a stimulating drink made of tree bark.
Looks to: is Impressed by.
Long Interval: an Interval twice the length of a usual one.
Lord Holder: A man who is in charge of a principal hold. The title is inherited and the Lord is responsible for the running of his hold and the well-being of its people. The holders in return supply the Lord with materials and generally do his bidding.
Mastercraftsman: The leader of a crafthall. There are many craftmasters, but only one Mastercraftsmen. However, all have the title 'Master'.
Numbweed: a salve which is used as an anaesthetic.
Oldtimer: one of the riders who Lessa brought forward four hundred Turns.
Pass: the time when the Red Star is close enough to drop Thread on Pern. Usually about 50 years in length.
Pern: the third of Rukbat's five planets.
Red Star: a planet which has an erratic orbit, passing Pern infrequently and dropping Thread on it.
Rukbat: a golden G-type star in the Sagittarian sector with five planets.
Runner beast: an equine adapted to Pernese conditions from fetuses brought frozen by the Settlers.
Settlers: The original humans who colonized Pern.
Sevenday: a Pernese week.
Shards: a Pernese oath meaning 'damn!'.
Shells: see 'Shards'.
Thread: a mindless organism dropped from the Red Star which devours all organic material. It can only be killed by starvation, water, extreme cold and fire.
Timor: Pern's smaller moon.
Turn: a Pernese year.
Watchdragon: The dragon and rider who have pulled watch duty on the Weyr roster. A 'watch' is four hours long.
Watchwher: A nocturnal, photosensitive relative of dragons used as a guard at night.
Weyr: A home of dragons and riders, usually an extinct volcanoe.
weyr: (note the small 'w') a dragon's den.
Weyrleader: Usually the rider whose bronze has flown the senior queen in a Weyr. He is in charge of the fighting wings of dragons and responsible for the training and discipline of dragonriders in his Weyr, and with the Weyrwoman the general running of the Weyr.
Weyrlingmaster: An ageing rider with good skills who is responsible for the training and discipline of weyrlings.
Weyrsinger: the harper for the Weyr, usually a dragonrider with harper training.
Weyrwoman: Usually the rider of the senior queen in the Weyr. She is in charge of the queen's wing during a Fall and the care of dragons and riders. She ensures tithes are satisfactory, appoints subordinates and with the Weyrleader is responsible for the general running and peace of the Weyr.
Wherry: a large, turkey-like bird.