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1.
the tenacious predisposition toward being a dumb ass. an alarmingly noticeable character trait in the lives of those whose general existence tends to disprove the theory "survival of the fittest." portmanteaux of dumbass and tenacity.
The CFO of our company added the number 29 and 30 and came up with a solution of 64; his general dumbacity is astounding.
by sandeebean96 February 13, 2008
 
2.
Arrogantly, stupid attitude or situation
1. Since my divorce, I have had to deal with so much dumbacity!
by mary987654321 August 21, 2008