Strong's #3975: muwrah (pronounced meh-oo-raw')
feminine passive participle of 215; something lighted, i.e. an aperture; by implication, a crevice or hole (of a serpent):--den.
Brown-Driver-Briggs Hebrew Lexicon:
ּ
me'ûrâh
1) light hole, den
Part of Speech: noun feminine
Relation: passive participle of H215
Usage:
This word is used 1 times:
Isaiah 11:8: "his hand on the cockatrice's den."