The two words tortuous and torturous have different core meanings. Tortuous means 'full of twists and turns', as in a tortuous route. Torturous means 'involving or causing torture', as in a torturous five days of fitness training. In extended senses, however, tortuous is used to mean 'excessively lengthy and complex' and hence may become indistinguishable from torturous： something which is tortuous is often also torturous, as in a tortuous piece of bureaucratese; their way had been tortuous and very difficult. Something which is torturous need not necessarily also be tortuous, however, but the overlap in sense has led to tortuous being sometimes used interchangeably with torturous, as in he would at last draw in a tortuous gasp of air.