Dirty Price
Dirty price (also called 'full price' or 'invoice price') is what you actually wire to the seller when you buy a bond. It equals the clean price (the quoted market price) plus accrued interest — the interest that has accumulated since the last coupon payment. Bonds are quoted using clean price so comparisons aren't distorted by coupon payment timing, but you always pay dirty price at settlement. For example, if a bond quotes at 98 (clean) with 0.5 in accrued interest, you pay 98.5 (dirty). The name 'dirty' is market slang reflecting that it includes the 'messy' accrued interest component.
Related Terms
Clean Price
The quoted bond price excluding accrued interest.
Accrued Interest
Interest that has accumulated since the last coupon payment, paid by the buyer to the seller.
Yield to Maturity (YTM)
The annualized return if you hold the bond to maturity, assuming all coupons are reinvested at the same rate.