The phrase "act of defining" is correct and usable in written English.
It can be used when discussing the process or action of establishing a definition for a term or concept.
Example: "The act of defining key terms is crucial for clarity in academic writing."
Alternatives: "process of defining" or "definition-making process".
At the same time, representatives treated the act of defining public debts as an important political matter.
In my experience, much of the marketing effort is in the act of defining customer personas.
It is then but a short step for the Ego to transcend its singularity through the act of defining an "ego" to be an entity performing that same function for itself.
The act of defining our future self can become self-fulfilling.
In "Defining Reality", Schiappa shows the act of defining to be a specialized and learned behavior, and therefore one that can be studied and improved.
Not only can the act of defining yourself feel validating, but academic studies suggest that activating positive self-images can help people of color and women be less likely to conform to negative stereotypes.
The United States Court of Appeals for the Second Circuit struck down the Defense of Marriage Act for defining marriage as between a man and a woman.
The Communications Decency Act gave the job of defining decency to courts, a bad idea since decency is so subjective.
The Dietary Supplement Health and Education Act of 1994 defined supplements as foods, not drugs.
The Higher Education Act of 1965 defined H.B.C.U.s as academically accredited institutions established before 1964 with the principal mission of educating black Americans.
The Wilderness Act of 1964 defined it many ways, and for camping purposes as "an area where the earth and its community of life are untrammeled by man".
