Strong’s Hebrew
H6940 — qadruwth
The entry below is Strong’s own definition (1890, public domain), and every verse where the word occurs.
קַדְרוּת
qadruwth — pronounced kad-rooth
from 6937; duskiness:--blackness. see H06937
1 occurrence in the KJV.
Isaiah 50:3
I clothe the heavens with blackness, and I make sackcloth their covering.