decisory

Decisory is an adjective meaning relating to or having the power to decide. It can describe a ruling, clause, factor, or act that determines an issue. The term derives from Latin decisorius, from decisus "decided," with the English suffix -ory; it shares roots with decisive and determinative, though decisory is now relatively rare outside specialized discourse.

In modern English, decisory is most often found in legal, historical, or linguistic writing. It may refer to the decisory power of a court, a decisory clause of a treaty, or the decisory sentence of a judgment—i.e., the decision that resolves a dispute. In philosophy or logic, decisory can denote a factor or proposition that settles a question. Because it is uncommon in everyday English, writers frequently substitute more familiar terms such as decisive, determinative, or dispositive.

Related terms include decisive, determinative, and dispositive, as well as the noun decisiveness. The use of decisory tends to emphasize the moment or act of decision rather than the process, and it is generally advised to consider audience and context when choosing between these synonyms.