Machiavellian /makēəˈvelēən/ adj. 

Definition: As a word, Machiavellian has only one definition: wily, conniving, and ruthless, particularly in the political arena.

To Machiavelli, the ideal ruler is one that finds a way to rule no matter the cost.

You’ll probably see Machiavellian and Machiavellianism in the same writings about the subject. This is just a way of making the famous person’s actions into a noun.

Etymology: Meet Niccolò Machiavelli, a 15th century Venetian (Italian) diplomat. He is most famous for his political paper called The Prince. Many view Machiavelli as the father of modern political science because of what he formalized in The Prince. This notoriety is a clue for why Machiavelli ended up with an “ian” after his name.

Machiavellian is a unique word in the English language, and there aren’t very many words of this caliber. The point is, what the person did is so influential that their actions are resolute through history.

In a Sentence

The Governor’s policies are Machiavellian.

The General moved his battalions around the battlefield with such precision that his Machiavellian nature comes through.

Her Machiavellian intelligence makes her the perfect presidential candidate.

Synonyms 

Cunning, Shrewd

Antonyms 

Scrupulous, Honorable