Rapid Roulette doesn’t refer to a term per se, but a variance of roulette.
This variance of roulette has the same layout as American Roulette but comes with one major twist — there are no outside bets. What this means is that you won’t be able to bet on red or black, odds or evens, low numbers or high numbers, or columns and dozens. The only types of bets available in Rapid Roulette are the numbers and neighbour bets.
The purpose of Rapid Roulette is to speed up the gameplay. It’s important not to mix up Rapid Roulette with Evolution Gaming’s Lightning Roulette since the latter has all the betting options available and its gameplay is sped up by reducing the waiting time after the ball has landed and the time the players have to make the bets.