impregnable /im-pregˈnə-bl/

1. That cannot be captured, broken into or taken by force
2. Which cannot be overcome, unassailable

impregnabilˈity noun

• benefactress
• benefactresses
• benefacts
• benefic
• benefice
• beneficed
• beneficence
• beneficences
• beneficent
• beneficential
• beneficently
• benefices
• beneficial
• beneficially
• beneficialness
• beneficialnesses
• beneficials
• beneficiaries
• beneficiary
• beneficiate
• beneficiated
• beneficiates
• beneficiating
• beneficiation
• beneficiations