The rigid pose a hunting dog assumes when pointing out game to a hunter.
The judge at the dog show took points off the Irish setter's dead set because its right ear twitched a few times.
A fixed or stationary condition arising from obstacle or hindrance; a deadlock.
to be at a dead set
(by extension) A determined effort.
I might not graduate first in my class, but I'll make a dead set at it.
Unswervingly dedicated; resolutely determined.
If John is dead set on marrying Catherine, his parents' objection will only provoke a falling out.
Complete and utter; total.
He is a dead set fool.