Forget carrying it in your purse -- now you can keep "Fifty Shades of Grey" where it matters most ... near your special lady place ... because TMZ has learned, the people behind the book just inked a massive women's underwear deal.

A rep for CopCorp Licensing tells TMZ, three apparel companies have just locked down the FIRST EVER licensing deals with author E.L. James to distribute "Fifty Shades"-themed clothes ... from t-shirts and hoodies ... to ladies' pantyhose, underwear, and pajamas.

According to CopCorp, FREEZE Clothing will be selling the knits, tees, and hoodies. A company called HYP will be selling hosiery, garters, and tights. And something called Briefly Stated will sell daywear, loungewear, and sleepwear (including underwear).

It's big news -- considering "Fifty Shades" is one of the most valuable licenses on the planet right now ... after the series sold more than 40 million copies worldwide.

Here's hoping the new merch comes with moisture protection.