Webster's Revised Unabridged Dictionary · 1913

Deathwatch

Deathwatch (?; 224) , noun

1.
(a) (Zoology) A small beetle (Anobium tessellatum and other allied species). By forcibly striking its head against woodwork it makes a ticking sound, which is a call of the sexes to each other, but has been imagined by superstitious people to presage death.
(b)
(Zoology) A small wingless insect, of the family Psocida, which makes a similar but fainter sound; -- called also deathtick.
She is always seeing apparitions and hearing deathwatches. — Addison
I did not hear the dog howl, mother, or the deathwatch beat. — Tennyson
2.
The guard set over a criminal before his execution.