The quality or state of being inappropriate.(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.
Use "inaptitude" in a sentence
"While there seem to be more and more programs to encourage girls who are interested in the sciences in engineering, old attitudes about the aptitude (or more accurately, inaptitude) of women in technical fields seem to be a long time in dying."
"McPalin - Never fail to rise above their own heights of inaptitude, McLame makes W. look like Einstien in his prime."
"Certain people interpreted this as a sign of the inaptitude of the female brain in this field."