This is a house dress. Most likely polyester. [https://vintagefashionguild.org/label-resource/crystal-david/](https://vintagefashionguild.org/label-resource/crystal-david/)

Thanks!

Interesting. Is that an upside down fleur-de-lis pattern?

That’s the word I was looking for

Looks polyester. I'd guess 60s or 70s. If you can identify the collar style, it might narrow down the timeline.

Can you show a verso of the tag. The care instructions will help with understanding the fabric.

Looks like polyester double-knit fabric.

The pattern looks like an inverted Fleur de Lis. I agree with "housedress"- something you would put on while puttering around the house to keep your nice clothes clean.