King’s College 2004 v Mistress Gunnvör sílfrahárr
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A Brief Look at Diminutives
*Old Norse names often form diminutives (pet names) based on one element
vDiminutives are formed from compound names most often by a sort of contraction and by changing a strong declension into a weak (usually in the second element, but sometimes in the first element of the name), or by adding -si, -ka, or the like.  Our best evidence for diminutives comes from runic inscriptions, as the sagas only rarely mention them.
vFeminine: Sigga from Sigríðr; Gunna from Guðrún; Inga from Ingunu; Imba from Ingibjorg; Gudda from Guðríðr; Manga from Margrot; Valka from Valgerðr; Ranka from Ragneiðr and Ragnhildr; Jóka from Johanna; Tobba from Þórbjörg; Sissa from Sigþrúðr; Kata (Engl. Kate) from Katrín; Kitta from Kristin; Asta from Ástríðr; þura from Þuríðr; Dura from Halldóra, etc.; Disa from Valdís, Vigdís, Herdís, etc.; Geira from Geirlaug; Fríða from Names in Frið- or -fríðr, etc.; Þrúða from Jarþrúðr, Sigþrúðr; Lauga from Guðlaug; Asa from Aslaug.
vMasculine: Siggi from Sigurðr; Gvendr from Guðmundr; Simbi from Signumdr; Brynki from Brynjólfr; Steinki from Steingrimr; Mangi from Magnus; Runki from Runólfr; Sveinki from Sveinn; Sebbi from Sigbjörn,Sveinbjörn (rare); Erli from Erlindr (Erlingr); Gutti from Guþormr,or rarely Guðbrandr; Kobbi from Jakob; Valdi from Þórvaldr; Mundi or Asi from Asmundr, etc.; Láki from Þórlákr; Leifi from Þórleifr; Láfi from Öláfr; Eyvi from Eyjólfr; Keli from Þórkell; Laugi from Gunnlaugr; Tumi (Engl. Tommy") from Thomas occurs in Icelandic as an independent name about the middle of the 12th century, and was probably borrowed from the English; Fúsi from Vigfús; Grimsi from Grímr; Jonsi from Jón (English Johnny); Björsi from Björn; Bensi from Benedikt.
*Diminutives appear to have moved into name stocks as personal names over time
vMany Viking Age personal names with a weak declension in -i were probably originally diminutives, e.g. Bjarni from Bjorn; Arni (Arne) from Örn; Bersi from Björn; Karli (Engl. Charley) from Karl; Jóra from Jóreiðr; Ragna from compounds in Ragn-, Ragneiðr; Ingi and Inga from compounds in Ing-; Goddi was probably from compounds in Goð- (Guðmundr) as the present Gudda of girls; Boddi (a name of the 8th century) from those in Böð- (A. S. Beadu); Daði (occurs in an Icelandic colonist family from the British Isles in the 10th century) probably from Davíð (Davy); Sebbi and Ubbi occur on Swedish Runic stones; Helgi (old form Hölgi) from Haleygr.
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