nap still has a meaning related to cloth.. Nap is most evident in velvet, or other textured cloth. If you run your hand on velvet, one way is smooth, the other way, (against the nap) you "fight" the smooth texture.
when making a garment, you want to make sure all the peices have the nap running in the same direction.
since nap reflects light differently, the pieces can appear to be different colors if you don't.
for a very long time, it was common to run nap down, that is, if you smoothed a velvet dress starting from the shoulder the hem, you were going with the nap. Nowday, it has become a style to run the nap up.
In Californian, (and NY) velvet dresses with nap running up are called "feel me up dresses" .(girl talk!)
nap is less notable in machine manufactured cloth, with a few exceptions like velvet, and some crepes. in hand woven cloth, any type weave can have a distinct nap. Woolens and silks are more likely to have naps than plant based cloth. so Nap is a term that has to do with how a peice of fabric lies..
