1. Literally, an envelope or small parcel containing an employee's earnings. Primarily heard in UK. Back when I started working here, before online banking and direct debit, everyone got their pay packet put in their hand at the end of each week.

2. By extension, a person's salary or rate of pay from an employer. Primarily heard in UK. The public outcry has been immense over revelations of the charity CEO's outrageous annual pay packet.