Questions about dresses bought at estate sale no. 3

hello all, recently came across a few dresses at an estate sale, i'll be posting the rest of them shortly. i was told that the woman had been 100 years old, i believe the clothing belonged to her. hoping to get some input on dating it each piece, along with any notable fashion terms i should know about the garments. any help would be much appreciated!

dress is worn, has tags, size 12
seems to be cotton
built in bra
plastic zipper

 

I agree with Susan.

 

I would also agree and can only add that it's missing a bright red belt, as per the belt loops.

 

Agree Melanie: I can see a thin red vinyl belt.

The dress looks very late '70s to me, perhaps 1980.

 

thank you, everyone! appreciate your help