Polypro

Short for polypropylene. A synthetic fabric material that wicks moisture away from the skin, and remains reasonably warm, even when wet. Polypro is a low-surface-energy plastic and it's difficult to get anything to stick to the surface. That includes antibacterial agents - hence polypro's famous ability to stink. Bacteria sticks well, though!

Alternatives include polyester knits (trade names include Polartec Powerdry and Patagonia's Capilene), polyester fleece, silk, and wool.

Remember: cotton kills!!