Etymology

Always derived from ON, cp. OIcel sker 'skerry, isolated rock in the sea' < *skerjan, cp. MLG scher 'rock, cliff', MHG scher (< st. v. *skeran- 'cut', cp. Icel skera 'cut, slaughter', OE scieran 'cleave, hew, cut', OFris skera, MLG skeren, OHG skeran). The absence of initial palatalization of /sk/ is a secure test of loan.

PGmc Ancestor

*skarjan

Proposed ON Etymon (OIcel representative)

sker 'skerry, isolated rock in the sea'
(ONP sker (sb.))

Other Scandinavian Reflexes

Far sker, Icel sker, Norw skjer, Dan skær, Sw skär

OE Cognate

Phonological and morphological markers

absence of palatalization of */sk/

Summary category

A1abc

Attestation

First attested in N place-names, e.g. Skertun, Lan. (EPNE), and then predominantly from N texts in ME. 

Occurrences in the Gersum Corpus

WA 4865

Bibliography

MED scā̆rre (n.2) , OED3 scar (n.1) , HTOED , de Vries sker, Mag. sker, Orel *skarjan, EPNE sker