Non-ProZ.com Apr 22, 2004:

Flere definitioner The distinctive packaging or design of a product that promotes the product and distinguishes it from other products in the marketplace -- for example, the shape of Frangelico liqueur bottles. Trade dress can be protected under trademark law if a showing can be made that the average consumer would likely be confused as to product origin if another product were allowed to appear in similar dress.

TRADE DRESS - the non-functional physical detail and design of a product or its packaging, which indicates or identifies the product's source and distinguishes it from the products of others.
Trade dress includes color schemes, textures, sizes, designs, shapes, and placements of words, graphics, and decorations on a product or its packaging.
A trade dress is non-functional if, taken as a whole, the collection of trade dress elements is not essential to the product's use or does not affect the cost or quality of the product even though certain particular elements of the trade dress may be functional.