lunitidal: lunar + tides (waves).

Tides are (not only, but mostly) caused by the Moon's gravity pull lowering the gravity reading on Earth if the Earth-Moon trajectory happens to bisect where you live. Basically, it means you weigh less, so water can rise and it creates the tides. Because the world isn't a perfect sphere (and more specifically, because the Moon doesn't hover each square inch of the planet uniformly), lunitidal intervals change over the whole planet.

I have attached a computation of all the moon rises and sets for 2010 in Athens (long. 37h 57m; lat. 23h 42m). The high point of the moon is between moonrise and moonset (so for example, today the moonrise will happen at 22:05, and will set at 09:19 tomorrow, thus moon up will be at (11 hours 14 minutes / 2 + moonrise) 3:42).

The next step is to look up the tide times for your area. Usually you can get this information in local newspapers, because that website is for Volos, which is what, 300km away from Athens? So get local times to be more accurate.

The lunitidal interval is the difference from moon up until the first high tide after moon up. 3:42 to 13:42 is 10 hours on the dot.

PS: I'm doing all this from memory, so google around and try to find some more information regarding the subject.