A misconception, A mistaken thought, idea, or notion; that one would never think of but had it been suggested, one would realize that it is a misconception.
Person A: is disconception a word?
Person B: NO. That's a common Disconception.
Person A: putting vodka into a water bottle turns it into water.
Person B: no it doesn't, what a disconception!
n00b: How do I make my laptop lighter, its too heavy?
techie: Delete the biggest files, every megabyte weighs .235 mg
techie: No. I'm kidding its a common disconception.