Wiktionary
coost
vb. (context obsolete or Scottish English) (en-pastcast)
Usage examples of "coost".
But he ne koude arryven in no coost Wher as he myghte fynde in this mateere Two creatures accordynge in feere.
Looke, what day that endelong Britayne Ye remoeve alle the rokkes, stoon by stoon, That they ne lette shipe ne boot to goon, I seye, whan ye han maad the coost so clene Of rokkes that ther nys no stoon ysene, Thanne wol I love yow best of any man!