the world > movement > motion in a certain direction > backward movement > [adjective] > returning towards point of departure > admitting of no return (3)
Admitting of no return; from, by, or through which there is no return. Now only poetic.
Admitting of no return; from which it is impossible to return.
From which there is no return (in various senses); without a means or mechanism for a return. †Also as adv.