Partially Convertible Debenture - PCD

See: Debenture. It's a bond backed by just a handshake. Not a milkshake. Then see: Convertible Bond.

This flavor of bond usually converts into stock at some set price. Like...one $1,000 par value of this bond converts into 25 shares of stock, such that the parity price is 40 bucks a share. With the stock at $35 now, you're happy to keep the bond. You'd lose money if you converted it, because 25 x 35 is less than a grand. So a partial convert means that you can convert, say, up to half of the bond, or up to a third, or up to 40% of the bond into shares at some set ratio, like the 25 shares to one bond unit or something like that.

So in this case, you can convert up to 10 shares with that 40% cap on partial conversion. You'd then have remaining 600 bucks of bond that would just go along until its principal was due, boringly pay off, and let you move on in life.