Etymology

cp. OIcel skærr ‘bright, clear, pure’, usually now derived < PGmc *skairi- (or *skairja-); there are no exact cognates beyond ON, but it should probably be connected to *skīr- (OE scīr ‘shining’, OIcel skírr, Go skeirs, OFris skīre, OS scīr(i), MHG schīr). 

PGmc Ancestor

*skairi- (or *skairja-)

Proposed ON Etymon (OIcel representative)

skærr ‘bright, clear, pure’
(ONP skærr (1) (adj.))

Other Scandinavian Reflexes

Far skærur, Icel skær, Norw skjær, ODan skiær, Dan skær, OSw skær, Sw skär

OE Cognate

Phonological and morphological markers

absence of palatalization of */sk/

Summary category

A1

Attestation

Fairly widespread throughout ME, though not common in the major late traditions (not in Chaucer).

Occurrences in the Gersum Corpus

Gaw 1261

Bibliography

MED skēr(e (adj.) , OED skere (adj. and adv.) , HTOED , Dance skere, Bj. 125, de Vries skærr (1), Mag. skær (2), Jóh. 810, Heid. skairi-