According to the Miriam-Webster Dictionary – Main Entry: 2felt. Function: transitive verb. Date: 14th Century. 1: To make out of or cover with felt. 2: To cause to adhere or mat together. 3: To make into felt or similar substance.
From About.com: Felting is the matting of wool fibers caused by a combination of heat, moisture, and agitation which causes the scales of the fibers to open up and lock together. Felting condenses the fibers, which causes shrinkage. Felting is irreversible. Also known as: Fulling – when the felting process is applied to a garment as a whole and not just its fibers.
Machine Felting/Fulling: making use of the agitating function of a washing machine to turn a garment made out of knitted fabric into a garment made out of felted fabric. This is done by knitting an oversize garment out of 100% animal fiber (i.e. wool, alpaca, angora) and putting it through an agitation cycle in a washing machine at the hottest setting, removing the garment when it reaches the appropriate size.
Making Felted Slippers: Something for Rebecca to do when she is Completely Freaking Out of Beads.