OK, sorry to be away for so long, but I've been out with a cold. Here are some definitions from my list, you guys already got some of them yourselves, of course - what else would I expect from such a group?
Advect - (verb) to be "dragged along" with the current. Little oceanic suspended things, like plankton, are advected - they move where the current goes - they can't swim of their own accord. Velocity can also be advected. (Now try and wrap your minds around THAT - I'm still not pleased with it myself!) The noun is "advection".
Bathymetry - this one was right - the measurement of ocean depth and ocean "features" (rifts and ridges and stuff)
Drogue - dammit, I have to look this up at school since this list had been compiled ages ago - It's a parachute-like thingy that is dragged along with the current and served some purpose in old-style current measuring instruments
Eddy - Jackie is right, swirly things. Specifically, eddies are called "mesoscale" features because they're neither tiny like surface waves nor "basin-scale" like the Gulf Stream. Usually about 100-600 km in diameter, they're self-contained swirly bits of ocean, extending to great depths (i. e. not just surface features).
Fetch - stales got this one (of course), the distance of open water across which wind blows, which affects the size of surface waves (bonus points for stales because he got that part, too)
Seiche - we pronounce this "SAYsh" - you guys collectively got this one, it's like a bathtub wave. It's a resonant wave in an enclosed area, like a harbour. It can have a number of causes but the net result is some pretty amazing changes in water level. My prof has some great photos of a seiche a few years ago in Petty Harbour, which also affected St. John's harbour, and by sheer luck the associated flow anomaly was measured by some ADCPs (Acoustic Doppler Current Profilers) moored in St. John's harbour.
Sill - this is a ledge of shallower water, for example, again in St. John's harbour, there is a sill. The harbour is about 30 m deep in the main part, but at the mouth of the harbour (the Narrows) there is a big ledge, where the depth is only 10 m or so. This has ramifications on how often the water "trapped" inside the harbour (in the part deeper than the sill) is flushed out into the sea.
Swell - this is specifically surface waves generated elsewhere, which will be obvious because they don't go in the same direction as the prevailing wind where you are observing them. They are easy to observe as the slow up-and-down of the water. If you pay attention you'll realize most of the time they are not going the same direction as the local wind. This means they were caused by a storm somewhere else, and have taken a fair bit of time to travel to where you are.
Thermocline - this one's been covered pretty well - it's the region of the sharp change in temperature that separates the upper ocean layers from the deep ocean. Typically this is at 200 m depth. The layer above the thermocline is well-mixed by surface winds but the layer below is unaffected by winds.
Turbidity - helen (I think it was her) got this one right one - no need to add to it.
Vorticity - the tendency of a fluid to move in a circle. It has a mathematical definition, too. It has important consequences for when eddies move into water of different depths, for example.
Doldrums - the region near the equator where winds are generally calm. There are oceanic/atmospheric reasons for this which I can't recall at the moment. Something to do with atmospheric cells (and of course Coriolis forces!)
Fjord - I'm sure most of us know this one but the word has a great ring to it - those steep ocean inlets like in Norway - and Newfoundland, and Labrador!
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