Demurrage (noun)- Believe it or not, I found this new word in a junk email!
“The term demurrage originated in vessel chartering and refers to the period when the charterer remains in possession of the vessel after the period normally allowed to load and unload cargo (laytime). By extension, demurrage refers to the charges that the charterer pays to the ship owner for its extra use of the vessel.” (Source: http://en.wikipedia.org/wiki/Demurrage)
Another reference reported demurrage as:
1. The detention in port of a vessel by the ship owner, as in loading or unloading, beyond the time allowed or agreed upon.
2. The similar undue detention of a railroad car, truck, etc.
3. A charge for such undue detention.
Used since 1640s from: Old French demorage, demourage; see demur
Source cited: http://dictionary.reference.com/browse/demurrage