noun

• (often used with “of”) A wide assortment; a varied multitude.
  "a rainbow of possibilities"
• (figurative) An illusion; a mirage.
  "Many electoral promises are rainbows, vanishing soon after poll day."
• (baseball) A curveball, particularly a slow one.
• (soccer) A trick in which the player makes the ball arc over the opponent's head using both feet; rainbow kick

adj

• (attributive, chiefly US) Made up of several races or ethnicities, or (more broadly) of several cultural or ideological factions.
  "That Asian-American actor Thomas Ikeda contributes a pleasingly frantic Panthino would not be considered rainbow enough."
• (attributive) LGBT.
  "Similarly, the question of who belongs in such a rainbow alliance isn't set. It can include gay men, lesbians, bisexuals and transgender individuals. It can include people who are 'questioning' which culture they belong to [...]"
• (poker, chiefly of a flop) Composed entirely of different suits.
• (mathematics, cryptography) Of or pertaining to rainbow tables.
  "rainbow attack"

verb

• (transitive) To brighten with, or as with, a rainbow; to pattern with the colours of the rainbow.
• (intransitive) To take the appearance of a rainbow.
  "We saw birds and butterflies rainbowing in the sun; lazy lizards crawling in the heat; inguanas blinking on stone wall, with mouth wide open for flies; poisonous snakes, not only carved on walls, but gliding through the grass."
• (climbing) 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.
  "“She's going to learn to belay while I'm climbing? What if I fall?” “You're not going to fall while rainbowing a 5.8, and besides, she'll catch you.” “I could die.” “That would be tragic,” I said. Kaitlyn crossed her arms."