Noah Webster
Obdurate
OB'DURATE, adjective [Latin obduro, to harden; ob and duro.]
1. Hardened in heart; inflexibly hard; persisting obstinately in sin or impenitence.
2. Hardened against good or favor; stubborn; unyielding; inflexible.
The custom of evil makes the heart obdurate against whatsoever instructions to the contrary.
3. Harsh; rugged; as an obdurate consonant. [Not used.]
OB'DURATE, verb transitive To harden. [Not used.]