morris-dance n.

traditional English dance of persons in costume, mid-15c., moreys daunce "Moorish dance," from Flemish mooriske dans, from Old French morois "Moorish, Arab, black," from More "Moor" (see Moor). It is unknown why the English dance (which typically is based on the Robin Hood stories) was called this, unless it is in reference to fantastic dancing or costumes (compare Italian Moresco, a related dance, literally "Moorish;" German moriskentanz, French moresque).