1. To show or say something is definitely true; to say that an arrangement or an appointment is definite. English = confirm.
2. Of an idea, agreement or plan, to be firm and clear, and to be unlikely to be changed. English = (be) definite.
3. To formally agree with a plan or an idea, if you are in a position of authority, and say that it can happen. English = approve.
4. To formally agree with a plan or an idea, especially a motion that has been presented to a meeting. English = adopt.