Dictatory

This decision is dictatory and irrevocable.

Source: tatoeba (11169838)

[B]ut rather, as I hope, for that our Engliſh, the language of men ever famous, and formoſt in the atchievements of liberty, will not eaſily finde ſervile letters anow to ſpell ſuch a dictatorie preſumption Engliſh.

Source: wiktionary

There is philosophercraft as well as priestcraft, both from one source, both of one spirit. In English cities and towns, the minister of religion has been tamed: so many weapons are bared against him when he obtrudes his office in a dictatory manner, that, as a rule, there is no more quiet and modest member of society than the urban clergyman.

Source: wiktionary

I have noticed many slight but most significant tokens of the fact, that, when in some occasionally critical emergencies it was quite important for the English to conciliate or draw into action with them any one conspicuous individual, party, or tribe of the Indians, the work was set about in a blundering, dictatory, or harsh way, which would seem likely to defeat the object aimed for.

Source: wiktionary