Imbecile

Imbecile was an insult used typically to suggest stupidity.

The Fourth Doctor shouted "Harry Sullivan is an imbecile!", before passing out from the effects of a rockfall on Voga – caused by Harry. (TV: Revenge of the Cybermen) The Twelfth Doctor referred to Z-67, a gas created by Sullivan for use against Zygons, as "the imbecile's gas". (TV: The Zygon Inversion)

Chancellor Padrac told Caleera that Sternbar was an imbecile, making her smile.

The Eleven called Councillor Alekall a "journeyman imbecile with ideas above his station". (AUDIO: Stop the Clock)