Fool

Fool was a insult used typically to suggest stupidity.

Androgar believed the War Doctor to be a fool for leaving a written warning to the Daleks in Arcadia. The Eleventh General disagreed, branding the Doctor a madman. (TV: The Day of the Doctor)

Professor Yana heard the voice of from within the Chameleon Arch call him a "human fool", ordering him to open the watch. (TV: Utopia)

Diane Holmes' lover gave her a "beautiful" dress as a gift, to which Owen Harper remarked that he was a fool for letting her go out in it alone. (TV: Out of Time)