I also came across this page

Middle English Dictionary

which has a 1434 reference to "morys letters" meaning arabic letters.

Moreis: also Morreis, Mourice.

There is a 1450 note in a verse "To the morre(ys) kyng he was a good post. For he was Constable of his Ost"

See also
"The Middle-English Versions of Partonope of Blois " where two different mansucripts are quoted.
The link to this was too long for the link maker.

Also a will in 1458 "Ciphos argenti sculpt cum morys daunce"

(reported elsewhere as possibly the first reference to Morris dance, in the 1458 Will of Alice Wetenhale (P.R.O.: PROB. 11/4) f. 205v, Lego Caterine filie mee..iij ciphos argenti sculptos cum moreys daunce cum unico cooperculo ad eosdem.)