Lower Midwest slang: contraction of being malignant AND ignorant all at the same time.
Beaufort was not only cantankerous, he was downright malignorant and liable to start a fight over practically anything and nothing.
I see this also as a portmaneau word consisting of malign and ignorant e,g, to use misinformation to denigrate someone or to ridicule something or someone based on a total disregard for the truth or facts. It can also imply malicious misuse or manipulation of the truth for personal gain.
Rick Perry's environmental advisers were unequivocably malignorant in their altered use of the scientists' presentation on climate change.
Being purposely stupid or obtuse with the express purpose of pissing someone off.
Don't be malignorant, you know I'm allergic to cats, but you put one in my coffee anyway.