An illusion, mirage.
A curveball, particularly a slow one.
In Texas hold 'em or Omaha hold 'em, a flop that contains three different suits.
Any prismatic refraction of light showing a spectrum of colours.
A multicoloured arch in the sky, produced by prismatic refraction of light within droplets of rain in the air.
A wide assortment; a varied multitude.
Rainbow trout.
Made up of several races or ethnicities, or (more broadly) of several cultural or ideological factions.
Multicolored.
LGBT.
Composed entirely of different suits.
Of or pertaining to rainbow tables.
To brighten with, or as with, a rainbow; to pattern with the colours of the rainbow.
To take the appearance of a rainbow.
In climbing gyms where the rocks to climb are colored to indicate suggested climbing routes, to climb rocks of different colors, thereby ignoring such routes.
A flickering light or lantern, especially over bogs, swamps or marshes, held by a supernatural creature who uses it to lure travelers at night to their demise.
A delusionary or otherwise unachievable goal that one feels compelled to pursue.