Answer: Either.

Explanation:
If something is valuable, it’s worth a lot — generally quantified in dollars. If something is invaluable it’s worth such a lot that we can’t assign a dollar figure to it. Something can be both valuable and invaluable, of course. But if we’re trying to say that something is priceless, invaluable will get our meaning across. (Priceless is another funny one — it looks like it should mean free, but it really means so valuable that a price cannot be attached — invaluable.)

As some people point out, these two words seem like they should mean the opposite of each other. However, we need to think of the valuable part of invaluable a little differently. Think of it as value-able, meaning “can have value assessed,” like “quantifiable” means “can have quantity assessed.” Invaluable, then, refers to something to which a specific value cannot be attached. Because we can hardly begin to imagine how high that value might be.

And that’s the word that critics of health information sharing systems to describe their value to health insurance companies.

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