what does "RO water" mean?

Being "slang challenged" I do not know what the "RO" in the phrase "RO water" means.

thanks for the help,
Max Blast

reverse osmosis
n.
A method of producing pure water by forcing saline or impure water through a semipermeable membrane across which salts or impurities cannot pass

Thanks Zandor. I've been lurking here for a while and have developed a developed a great respect and admiration for your giving and helpful nature.

Hope you are feeling better these days.

Max Blast