1. Impossible to get in or through: Not able to be passed through or entered.

2. Incomprehensible: Impossible to understand or discern.

3. Closed to influence: Not open to intellectual or moral influences, impressions, or ideas.
1. The woods formed an impenetrable barrier.
2. An impenetrable legal jargon.
by Jafje March 31, 2007
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A large amount of hair located around the buttocks and anal region. Some people decide not to shave this region due to the fact that it renders the individual immune to any attempts at sodomy.
Dude 1: "Yo man, I heard your homeboy just got out of the pen, did he get it up the butt at all?"
Dude 2: "Nah doggy, that mutha fucka's ass has an impenetrable bush, no one got near that shit."
by Da Vin Chee December 22, 2009
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A woman, or man, who is so 'untouchable' that she seems to be an impenetrable fortress.
Ryan: Damn, see that impenetrable fortress over there?
Andrew: Ouff man, you don't stand a chance.
by Kldcs Nerd November 26, 2009
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Inability of a man to penetrate his penis into the vagina of his partner due to various factors like erectile dysfunction.
The guy is down in the dumps because he has recently developed impenetrance.
by uttam maharjan January 30, 2010
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