Skellige jargon is the language used on the Skellige. It's based on the Elder Speech of Aen Seidhe elves but has undergone many changes to suit the Islanders. For example, questions are formed by adding "ell'ea" at the end of the sentence, in a manner considered impolite in classical Elder Speech.
During the formative centuries, Skelligers had their own runes
but apparently adopted the  modern alphabet or First Runes at some point later on.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Names Phrases
of (appears to be just general genitive, not marking solely hereditary ties)
oath, curse ( geis is a magical obligation/prohibition in Irish mythology. Also; geas, geasa)
fortress, castle, keep, watchtower
 chief judge
 skald, courtly poet
 to swarm
of (from below)
Cuach op arse, ghoul y badraigh mai an cuach...
Crazy up the arse, a ghoul of [battle ?], a crazy mother... (meaning of "badraigh" is unknown; it may be based on an Old Norse "bardagi", word for battle or beating)
Aen me Glaeddyv, zvaere a' Bloedgeas, Ard Rhena, Lionors Aep Xintra!
By my sword, I swear Blood Oath, the Highest Queen, Lioness of Cintra!
Skugga! Svarm! Vattna halla! Blota himmel, blota mylla, braka och blixtar! Blota himmel! Blota mylla!
 Shadow! Swarm! Water the frost! Wet sky, wet soil, crack and lighten! Wet sky! Wet soil!
Apart from using altered words of the Elder Speech, based mainly on Celtic languages, Andrzej Sapkowski's language of the Islanders draws heavily from Norwegian and Danish.
In , the language is said to be hard to distinguish from the Wiedźmin: Gra Wyobraźni Nilfgaardian language. This may allude to a minor Dutch influence as the Nilfgaardian is classically full of it.
After being asked by a fan, CD Projekt's narrative designer Mateusz Tomaszkiewicz confirmed Skelligan language used in their games references several different Scandinavian dialects.
 The storytellers at R. Talsorian Games seconded this in by stating that Skelligan names − and by extension the jargon − are generally Scandinavian.
The Witcher Role-Playing Game
Blood of Elves ↑
2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12
The Witcher 3: Wild Hunt
The Tower of the Swallow ↑
4.0 4.1 4.2
Wiedźmin: Gra Wyobraźni ↑
The Witcher Role-Playing Game ↑
Mateusz Tomaszkiewicz about Skellige jargon and Nilfgaardian