Definition of "impenetrability" [im•pen•e•tra•bil•i•ty]

• The quality or condition of being impenetrable. (noun)
• The inability of two bodies to occupy the same space at the same time. (noun)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "` I meant by "impenetrability" that we've had enough of that subject, and it would be just as well if you'd mention what you mean to do next, as I suppose you don't mean to stop here all the rest of your life. '"
• "Ideas never admit of a total union, but are endowed with a kind of impenetrability, by which they exclude each other, and are capable of forming a compound by their conjunction, not by their mixture."
• "`I meant by "impenetrability" that we've had enough of that subject, and it would be just as well if you'd mention what you mean to do next, as I suppose you don't mean to stop here all the rest of your life.'"