In shipping terms, what is a "cube"?

It depends. A "cube" in general is a freight shipping term. If you are talking International air or ocean freight it's usually 1 Cubic Meter. If you are talking Inland freight in the US it's usually 1 Cubic Foot. Since you are dealing with an overseas supplier I'd guess a cubic meter but you need to verify with the supplier.

It's a way to measure frieght volume, it doesn't mean, for example that it's exactly that dimension just that volume.

If it's an odd shape the cube goes out the window and the freight companies ask you to bend over.

There are two other calculations on the product that factor into freight cost:

Weight and value.

If you are dealing with expensive stuff they ask for more money (freight is crazy man).

Your shipment volume (how much business, not how much product volume) will determine what discount you get (which is important, trucking stateside starts at a discount rate of about 65%).

You need to find out what the freight class of the product you will be dealing with is before you do inland quoting.

Thanks mucho!

Craven wrote: "freight is crazy, man."
I'm not sure I understand how "value" comes into play but I do understand weight and volume.
A cube is, I've been told , a unit of measure that takes up an equal proportion of weight capacity and space capacity in a truck. If the cube is in balance, you can get the hefty discounts craven mentions (more about that later).
But say you are shipping 20,000 pounds of feathers or 5,000 pounds of anvils. Your cube in either case is away from the norm: too much space relative to the weight or too much weight relative to the space.
Discounts from the published rates are certainly negotiable but a lot depends on where you are. If a trucking company is taking a lot out stuff out of your area but is coming in with underloaded trucks, you can get the 60-80% discounts craven mentions on incoming freight but you probably won't get much of a deal on outgoing.
This post is already too long but I'd like to tell you a story of how trucking has changed the competition in one facet of my business. Any takers?

Do tell!