reverie

Etymology 1

From French rêverie.

noun

1. A state of dreaming while awake; a loose or irregular train of thought; musing or meditation; daydream.
   we sat / But spoke not, rapt in nameless reverie, […] 1847, Alfred Tennyson, The Princess, Canto VII, lines 107-108
   Within the branching shade of Reverie / Dreams even may spring till autumn; yet none be / ⁠Like woman's budding day-dream spirit-fann'd. 1899, Dante Gabriel Rossetti, “The Day-Dream”, in Pictures & poems
   He fell into a reverie, a most dangerous state of mind for a chauffeur, since a fall into reverie on the part of a driver may mean a fall into a ravine on the part of the machine. 1913, Robert Barr, chapter 3, in Lord Stranleigh Abroad
   Even the blithely unselfconscious Homer is more than a little freaked out by West’s private reverie, and encourages his spawn to move slowly away without making eye contact with the crazy man. June 3, 2012, Nathan Rabin, “TV: Review: THE SIMPSONS (CLASSIC): “Mr. Plow” (season 4, episode 9; originally aired 11/19/1992)”, in (Please provide the book title or journal name)
2. An extravagant conceit of the imagination; a vision.
   If the minds of men were laid open, we should see but little difference between that of the wise man and that of the fool; There are infinite reveries , numberless extravagancies , and a perpetual train of vanities , which pass through both . November 17, 1711, Joseph Addison, The Spectator No. 225

Etymology 2

From Middle French reverie (“revelry, drunkenness”), from Old French resverie, from resver (“to dream, to rave”), of uncertain origin. Compare rave.

noun

1. (archaic) A caper, a frolic; merriment.