Accretion is the gradual process of growth by the addition of new parts. A company is said to be accretive if it increases in size either through organic growth or by acquisitions. An acquisition is said to be accretive if it adds to earnings per share; if the acquisition adds more value than it costs. Accretive can also refer to an increase in the notional principal amount of a financial instrument over its life. For example, the accumulation of capital gains on a bond, bought at a discount, in anticipation of receipt of its full par value at maturity. The opposite of amortization.