It just means "small coat".
You hear it and you think "oh yeah, a petticoat, it's that fashionable overcoat popular in the 1700s!" Wrong! Who on earth was in charge of naming the petticoat? Wrong in just about every way.Our point is, this "thing" which we call a "petticoat" is a great accessory for any dress, giving you that extra oomph and volume to really show it off! Obviously that maybe gets confusing because underwear is still a thing, but our point is that petticoat is a very bad name for describing what this is. And whoever it was, what on earth were they thinking? Women's Plus White Petticoat Seriously, you know where petticoat came from? It's not a skirt, but it is something you wear around your waist.Any ideas?" Why not call it an underskirt, like underpants? "Okay guys, we've named the pencil, so now let's talk about this underskirt thing all the ladies are wearing.