English word aforethought comes from English thought, English afore- (Previously.)

Detailed word origin of aforethought

Dictionary entry	Language	Definition
thought	English (eng)	(uncountable) The process by which such forms arise or are manipulated; thinking.. A way of thinking (associated with a group, nation or region).. Form created in the mind, rather than the forms perceived through the five senses; an instance of thinking.
afore-	English (eng)	Previously.
aforethought	English (eng)	(postpositive) Premeditated; planned ahead of time.

Words with the same origin as aforethought