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im·preg·na·ble 1

1. Impossible to capture or enter by force: an impregnable fortress.
2. Difficult or impossible to attack, challenge, or refute with success: an impregnable argument.

[Middle English imprenable, from Old French : in-, not (from Latin in-; see in-1) + prenable, pregnauble, pregnable; see pregnable.]

im·preg′na·bly adv.

im·preg·na·ble 2

Capable of being impregnated.

American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Adv.1.impregnably - in an impregnable manner; "the sight of that bland, impregnably righteous face has been enough to make their blood run cold"
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in classic literature ?
Finally, though, as will soon be revealed, its contents partly comprise the most delicate oil; yet, you are now to be apprised of the nature of the substance which so impregnably invests all that apparent effeminacy.
In his inauguration address in April 1789, President Washington recommended that the Constitution be amended to make certain that "the characteristic rights of freemen" might be "impregnably fortified." (116) Once the Constitution was secured, Madison was willing to make changes, not impairing the national structure, in order to bring the two states, Rhode Island and North Carolina, which had not yet ratified, and, indeed, to convince the minority that the Constitution was as wise as the majority saw it.
As he signed the ( Revenue Act of 1932  into law, ( President Herbert Hoover  lauded "the willingness of our people to accept this added burden in these times in order impregnably to establish the credit of the federal government."
(231) In his first inaugural address, Washington called for amendments to make certain that "the characteristic rights of freemen" might be more "impregnably fortified." (232)
He said Prime Minister was punished on making country's defence impregnably. Prime minister was ousted from the country.
At their zenith they appear impregnably all-powerful.