One who sits in a committee with no knowledge of the subject but offers an opinion to justify their presence.
She/he had to pontificate for half an hour, trying to justify being present at the meeting. There's a half hour we'll never get back, thanks to that "commidiot!"
When someone (Commidiot) on a committee or the entire committee (Commidiots) cannot make up their mind or their minds on anything.
Either there is one person who holds the entire committee back as they want to feel superior and tell people what to do because they are a control freak and need to stroke their own ego.
Or the entire committee can't come to a conclusion about what the hell it is they want, need or have to accomplish. Usually with time constraints attached, this is when commidiots shine the brightest.