The term 'surplus amount' can be defined as the amount of money or resources that are left over after all expenses have been paid. This term can be represented by two words in a crossword puzzle: 'OVERAGE' (7 letters) and 'RESIDUAL' (8 letters). OVERAGE is defined as an excess of something, while RESIDUAL is defined as something that remains after the greater part has gone. Both terms refer to the same concept of surplus amount.