crackbrained

Yes, everybody in this world is a little crackbrained, but at least I don't bore other people.

She had no right to use such a power for the propaganda of crackbrained theories!

They were of a very various kind, and no bad epitome of the mind of a gallant and crackbrained coxcomb.

This p. 83came from a hundred children collected by a crackbrained stranger (said to be English).

Nobody disputed it; or, if any one did, he was set down by the oracles of the vicinage as a crackbrained visionary.