I think it’s that it is not consumable.
George Reisman writes that capital goods are consumable. The difference is “productive consumption” versus “unproductive consumption”. You need to consume flour during the process of producing bread, for example.
Factory machinery is also consumed during production processes.
That’s why I like my definition better. A capital good is something that contributes to the production of a consumer good but is not itself part of the consumer good.
Clayton -
Indirectly servicable goods are factors of production, and include both original factors (land and labor) and capital goods. All action requires factors of production and ends with consumption.
Strictly speaking, capital goods are not only producible (it has been produced, not merely the idea), but they are nonpermanent. If someone creates something, and it lasts forever, then it is land.
In terms of praxeology and simple actions, it still holds. You are sitting on your couch and decide to consume an apple. In terms of this end, the apple in your refrigerator is a capital good, it has been produced, will deteriorate, and is indirectly servicable. Only when the apple is in your hand and you are eating is it then a consumer good.
Now if you were stranded on an island and you wanted an apple, the apple attached to the trees is indirectly servicable and nonpermanent. However, although it can be produced (if you discover the recipe), it has been made by nature, and is therefore land (IMO). Once you discover the recipe and make some apple trees of your own, only then does it become a capital good. For the pilgrims, the agriculture they initially found when they settled in the new world was land. Only when they started to make some of it did it become a capital good.
To all:
Great posts. 
Autolykos:
I eat the apple to have energy to be able to use my labor with equipment so that I can do my job and get paid as a result.
If we consider labor the original capital good (as someone suggested) then we can consider the eating to just be a means to help achieve an intermediate end.
Yes, of all of these definitions, I like this one best. It is a good used in the process of producing the final consumption good, but I think that some of the accounting verbiage is useful as well. A capital good is persistently used to produce, it isn’t used only one time. Dynamite is not a capital good. A steam shovel is a capital good.
Dynamite is not a capital good
Typically speaking; what kind of a good is dynamite? a consumer good?
Intermediate good.
dynamite is a capital good, it is just circulating capital instead of fixed capital.
As was said before, people tend to have different definitions. I generaly define it as any good used in the production of other goods and/or services.
Whether a good is a capital or consumer good depends not only on its intrinsic properties, but also how its used. For example a computer used to keep track of a store’s inventory is a capital good, but a computer used to play World of Warcraft is a consumer good.
Anyone here read Capital and It’s Structure. I only did one quick read on it. I can’t say I disagree with it.