Rasse (n.) - a raised mound or eminence, a cairn of stones.
Bot yet the styffest to start bi stoundez he made,
Til at the last he watz so mat he myght no more renne,
Bot in the hast that he myght he to a hole wynnez
Of a rasse bi a rokk ther rennez the boerne.
- Anonymous: Sir Gawain and the Green Knight (1400)
The Middle-English Word of the Day is selected from Mayhew and Skeat's
"Concise Dictionary of Middle English."
As found on Greg Lindahl's website
The example text was found at the Middle English Collection of the University of Virginia Library.