formalize

verb

1. (transitive)To give something a definite form; to shape.
2. (intransitive)To develop into a definite form.

   “We have more fun and exciting fundraisers planned, and we're trying to carefully budget them so they don't cut into your life savings. As they formalize, we'll widely publicize these events.”

3. To give something a formal or official standing.
4. To act with formality.
5. To rigorously prove a mathematical result.