The clean price of a bond is without accrued interest, the dirty price is with. The total cost includes commissions, accrued interest, and taxes, in addition to the principal amount of the securities traded.  When you buy bonds between interest payment dates and pay accrued interest to the seller, this interest is taxable to the seller. The accrued interest that you paid should be subtracted from your taxable interest. 
Accrue 15c from "growth, increase, what has grown to increase.  Interest 15c originally meant to compensate for loss, later compensation due from a defaulting debtor. Financial sense of money paid for the use of money lent 1520s. Interest rate by 1959.