Please raise your hand if you remember either your grandmother or mother wearing these. Enaguas are slips. A slip is a feminine undergarment similar to a skirt that serves as a lining for when one wears sheer dresses/skirts. The older enaguas from earlier generations are pictured as ruffled cotton undergarments, but the most popular contemporary ones are made out of nylon microfiber or polyester with a lace trim on the hem.
They are thin and airy. Some people find them comfortable. I don't know about you, but I hated those things! When I was a little girl, my mom got me one and it was really big on me (I was a late bloomer) so the enagua would come down and you could see it over the dresses borderline that resulted in a bad fashion statement not making this fashionista happy at all. Of course, I forgave my mom under one condition—that she never made me wear one again!