i Register
In some senses, tailwind is marked as figuratively. Watch for register when choosing this word.
noun
A wind that blows in the same direction as the course taken by an aircraft, sailing ship, bird, etc.; a following wind.
A force that accelerates progress.
verb
Of a wind, to blow on a windmill or wind turbine in such a way that wind pressure is exerted on the wrong side of the sail or turbine assembly.