1650s, "authoritative utterance," from Late Latin dictationem (nominative dictatio) "a dictating, dictation," noun of action from past-participle stem of dictare "say often, prescribe," frequentative of dicere "to say, speak" (from PIE root *deik- "to show," also "pronounce solemnly"). Meaning "act or practice of expressing orally for another to write down" is by 1727.
he signed and mailed his dictation without bothering to read it
dickering
dickhead
dicky
Dictaphone
dictate
dictation
dictator
dictatorial
dictatorship
dicte
diction