dead on one’s feet

Extremely tired. This graphic hyperbole, with its use
of “dead” in the meaning of “utterly fatigued,” is probably related to dead
tired, where “dead” means “very” or “absolutely.” This locution has been
traced to Irish speech and appears in such clichés as dead wrong for “com-
pletely mistaken,” dead right for “absolutely correct,” dead certain for “totally
sure,” and others. “Dead on one’s feet” became common in the mid-
twentieth century. John Braine used it in Life at the Top (1962): “Honestly,
I’m dead on my feet.”