impenetrable Meaning, Definition & Usage

  1. adjective not admitting of penetration or passage into or through
    • an impenetrable fortress
    • impenetrable rain forests
  2. adjective satellite permitting little if any light to pass through because of denseness of matter
    heavy; dense.
    • dense smoke
    • heavy fog
    • impenetrable gloom
  3. adjective satellite impossible to understand
    • impenetrable jargon

WordNet

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

Webster 1913