Etymology

cp. OIcel villr ‘wild; bewildered, erring, astray’ < PGmc *welþja- (now usually preferred, but most earlier etymologies < *wilþ-); cp. OE wilde, Go wilþeis, OFris wilde, OS, OHG wildi ‘wild’. 

PGmc Ancestor

*welþja-

Proposed ON Etymon (OIcel representative)

villr ‘wild; bewildered, erring, astray’
(ONP villr (adj.))

Other Scandinavian Reflexes

Far villur, Icel villur, Norw vill, ODan willær, wild(ær), Dan vild, OSw vildær, Sw vill, vild

OE Cognate

wilde 'wild, untamed, uncontrolled' 

Phonological and morphological markers

ON consonant cluster assimilation

Summary category

A1*c

Attestation

Mainly N and E in ME, but also the Irish text a1500 Conq.Irel.(Rwl B.490)); MnE Sc. dial.

Occurrences in the Gersum Corpus

Gaw 2084; WA 1272; Pat 473

For the sense of Gaw 2084, OED (sense 5) prefers ‘out-of-the-way, unfrequented, desolate’ (followed by Wright 1935: 349-50).  Understood as the second element of a compound welawylle by Madden, Morris, M(G) and GDS (‘wondrous wild’) (followed by Kullnick 18, Schmittbetz 14); but this was rejected by Emerson 1922: 2084, TGD and most subsequent editions (see further Vant 518n), but for a defence see PSn (‘very wild’) and McGillivray.

Bibliography

MED wil (adj.) , OED will (adj. (and adv.)) , HTOED , EDD will (adj., adv., v.1 and sb.2) Dance wylle, Bj. 170, de Vries villr, Mag. villur, Bj-L. vill, Heid. welþja-, Orel *welþjaz, Kroonen *welþja-, AEW wilde