It may not at once come to mind, but this archaic word is a close cousin of array. The ending in both cases is a Germanic root that means to prepare or get ready. To array originally meant to place in readiness or to prepare — troops arrayed for battle were ready with all their equipment; to deray was almost its opposite, meaning to provoke disorder, disturbance, tumult or confusion.
You won’t know the verb, as it vanished from the language in the fourteenth century. The noun lasted a little longer but likewise disappeared, only to be dragged back into use in the early nineteenth century as what the Oxford English Dictionary describes paradoxically as “a modern archaism”. At once that makes one think of Sir Walter Scott, and he doesn’t disappoint:
The whole front of the house was lighted, and there were pipes and fiddles, and as much dancing and deray within as used to be at Sir Robert’s house at Pace and Yule, and such high seasons.
Redgauntlet, by Sir Walter Scott, 1824. Pace is an old Scottish and northern English dialect term for Easter, also at one time called Pasque or Pasch, which is ultimately from the Hebrew word for Passover that also gave us paschal.
The fixed phrase dancing and deray outlasted other appearances of the word, though it is now defunct as well; it meant disorderly mirth and revelry at a dance or some similar festivity.