and, oh, by the way, felt is not woven
(see : http://en.wikipedia.org/wiki/Felt)
but woven fabric can be felted....

with the agitation and water and sometimes also soap,
the fibers can be caused to bind together to make a
matted surface...which is why you should never wash
a wool sweater in hot water unless you want it to
shrink and become felted...

http://en.wikipedia.org/wiki/Fulling