1. Able to withstand attack; SYN. inviolable secure strong unassailable unattackable.
2. Impossible to take by storm; SYN. inexpugnable.
3. Able to withstand attack; capable of being fertilized; able to become or be made pregnant.
ETYM Latin inexpugnabilis: cf. French inexpugnable. Related to In- not, and Expugnable.
Incapable of being subdued by force; impregnable; unconquerable.
Not able to be attacked or captured.
In an impregnable manner.