Etymology

Formed on the same stem as rapes; cp. the adj. Sw dial. rap, rapp ‘quick’ and the adv. OIcel hrapalliga ‘hurriedly, headlong’ (< *hrap- perhaps via the noun hrapaðr ‘hurry’ or an adj. *hrapall; see Mag.).

PGmc Ancestor

*xrap- 

Proposed ON Etymon (OIcel representative)

cp. hrapalliga 'hurriedly, headlong' 
(ONP cp. hrapal-liga (adv.), hrapaðr (sb.))

Other Scandinavian Reflexes

Sw dial. rap, rapp ‘quick’ 

OE Cognate

Phonological and morphological markers

Summary category

B2a

Attestation

Fairly widespread in ME from the early 14c., but esp. characteristic of alliterative verse.

Occurrences in the Gersum Corpus

Gaw 2219; Pe 363, 1168

Bibliography

MED rāp(e)lī (adv.) , OED rapely (adv.) , HTOED , Dance rapely, Bj. 251