An example of decisive is a person who always makes up her mind firmly and quickly.
An example of decisive is the information gained from a student's success in the classes which they take to determine their interest in their major field of study.
The decisive battle in the war; the decisive piece of evidence in the lawsuit.
A decisive leader.
A decisive moment in his career.
A decisive tone of voice.
A noble instance of this attribute of the decisive character. -J. Foster.