Couth past, past part. Could; was able; knew or known; understood. (Obs.) "Above all other one Daniel He loveth, for he couth well Divine, that none other couth; To him were all things couth, As he had it of God's grace."
... Chaucer whan ye mete As my disciple and my poete, For in the floures of his youth, In sundry wise as he well couth, Of dittees and of songes glade, The which he for my sake made, The lond fulfilled is ... — A Literary History of the English People - From the Origins to the Renaissance • Jean Jules Jusserand