See: Floater.
Outside the bathroom, the term "floater" describes a debt security (like a bond) where the coupon payments (the regular income generated by the security) change with some measure of overall rates. Usually, this measure is an interest rate index, like LIBOR. So if the rate index goes up, the coupon payment goes up...and vice versa.
A reverse floater has the opposite relationship. Like a floater, the coupon rate is tied to some interest rate index. But, in this case, an increase in the rate index produces a decline in the coupon payment...or vice versa. The relationship between the coupon and rate index is inverse.