A multiplier is a numerical way of measuring how important one industry is to other industries in the region, this is commonly shown as the total amount of expansion in a region as a result of a investment of earnings, jobs or sales. In other words, a multiplier of 2.5 is made up of the initial unit (e.g £1.00) and the further yield (£1.50).
Source: EMSI’s model. See What is a multiplier?