Lululemon alleges that Costco has stolen the intellectual property of its Scuba hoodies and sweatshirts, Define jackets and ABC pants.

In a lawsuit filed on Friday, Lululemon claimed certain Costco products have "unlawfully traded" on the brand's "reputation, goodwill and sweat equity by selling unauthorized and unlicensed apparel employing knockoff, infringing versions" of its clothing line.

The Canadian athleticwear retailer filed a lawsuit against the retailer for selling products it says are confusingly similar to its own.