Website alert: In an account of a 1908 wedding I've just read, the bridesmaid was said to have worn a "white lingerie gown." Whoa. Not her underwear or nightgown, but what? Short, short answer is a lightweight dress made of cotton or linen characterized by pleats, tucks, and lace, as I learned in a beautifully illustrated post, Terminology: what is a lingerie dress or lingerie frock? (and blouse, and skirt) at The Dreamstress website. The same website has a splendid glossary of textile terms with links to longer posts like this one.
Oh, and what did my bride wear? "… a long veil of tulle caught with a spray of orange blossoms. Her dress was white satin, trimmed in princess lace, fashioned empire, with a long train. She carried a bouquet of bride's roses with a shower of lilies of the valley."