From: Piotr Gasiorowski
Message: 2671
Date: 2000-06-18
A complete solution of the SISTER/COUSIN puzzle, step by step.
PIE *sweso:r, gen. *swesr-os gives Latin *soror/*soro:r-is. In the first syllable we have the typically Latin change of *swe- into *so-, with the vowel coloured by the labial-velar glide (as e.g. in *swepnos > somnus ‘sleep’). Intervocalic *s became voiced (>*z) and eventually ‘rhotacised’ (>*r) in Latin. The historical long *o: of the nominative survived in the analogically reformed non-nominative cases, while in the nominative itself it underwent a relatively late change known as the Classical Latin iambic shortening (after a light syllable).
PIE *sr changed into Proto-Italic *θr, which developed into Latin fr word-initially, but was voiced medially, yielding *ð
r > *vr > br. Here are a couple of examples:*sri:gos- > fri:gus/fri:goris ‘frosty weather, coolness’
*mems-r- ‘meat, flesh’ > membrum ‘limb, body part’
*krxs-r-on- > cra:bro: ‘hornet’
Had the original oblique-case stem *swesr- survived in Latin, it would have produced *sobr- (*sobris, etc.). In fact, a similar form appears in derivatives based on the vriddhied (long-vowelled) adjective *swe:sro- ‘sisterly, belonging to a sister’. Those words lived independent lives and were not affected by the changes that levelled out the case forms of soror. Latin inherited *swe:sr-i:n-o- > so:bri:nus (m.)/so:bri:na (f.) ‘cousin-german on the mother’s side’. This term survives in Spanish with a semantic shift (sobrino/sobrina ‘nephew/niece’).
So:bri:nus gave rise to con-so:bri:nus ‘co-cousin’, originally used of children of two sisters, then more loosely of any collateral relation more remote than brothers or sisters. In the transition from Latin to French much of the phonological substance of consobrinus/consobrina was eroded away. By Old French times it had already been slimmed down to cosin/cosine, borrowed into Middle English as cosin [kuzin].
Piotr