'Impenetrable' definitions:

Definition of 'impenetrable'

From: WordNet
adjective
Not admitting of penetration or passage into or through; "an impenetrable fortress"; "impenetrable rain forests" [ant: penetrable]
adjective
Permitting little if any light to pass through because of denseness of matter; "dense smoke"; "heavy fog"; "impenetrable gloom" [syn: dense, heavy, impenetrable]
adjective
Impossible to understand; "impenetrable jargon"

Definition of 'Impenetrable'

From: GCIDE
  • Impenetrable \Im*pen"e*tra*ble\, a. [L. impenetrabilis; pref. im- not + penetrabilis penetrable: cf. F. imp['e]n['e]trable.]
  • 1. Incapable of being penetrated or pierced; not admitting the passage of other bodies; not to be entered; impervious; as, an impenetrable shield. [1913 Webster]
  • Highest woods impenetrable To star or sunlight. --Milton. [1913 Webster]
  • 2. (Physics) Having the property of preventing any other substance from occupying the same space at the same time. [1913 Webster]
  • 3. Inaccessible, as to knowledge, reason, sympathy, etc.; unimpressible; not to be moved by arguments or motives; as, an impenetrable mind, or heart. [1913 Webster]
  • They will be credulous in all affairs of life, but impenetrable by a sermon of the gospel. --Jer. Taylor. [1913 Webster]

Words containing 'Impenetrable'