Ordinary Gweilo

I was recently asked what “invaluable” means.  Simple enough, but also rather puzzling when you consider that in+valuable should mean not valuable, as in words such as inconsistent and inexact.

The explanation is that valuable used to mean something that you could value (in contrast to something that is impossible to value, or priceless).  So you might have said that a pound of potatoes was valuable (because we can calculate its value), whereas good advice was invaluable.

Of course, valuable has now come to mean something with a high value – though it is often used almost interchangeably with invaluable, thus causing great confusion to anyone trying to learn English.   See also: flammable and inflammable.