actact2 verb [intransitiveI]1act as something to do a particular job or have a particular roleWe will act as the company’s agent for the sale.
Mortgage brokers act as middlemen between borrowers and lenders.
2act for somebodyLAW if a lawyer acts for someone, he or she represents them in a legal casethe lawyer acting for the insurance company
3act on somebody’s behalfCOMMERCELAW to represent someoneThe two parties may agree a price for the land or ask an agent to act on their behalf.
4act on something to take action as a result of something that has been said, written, suggested etcCongress is eager to act on the report.
The administration hasn’t yet acted on the request.