impregnability

impregnability (uncountable)

1. The quality or state of being impregnable; invincibility.

• William Dwight Whitney, Benjamin E[li] Smith, editors (1911), “impregnability”, in The Century Dictionary […], New York, N.Y.: The Century Co., →OCLC.
• “impregnability”, in Webster’s Revised Unabridged Dictionary, Springfield, Mass.: G. & C. Merriam, 1913, →OCLC.