Tea Gowns vs. Lingerie Dresses
Start searching for the ubiquitous Edwardian white cotton & lace dresses online, and you’ll quickly find a name for them: tea gowns. There are hundreds on etsy by that name. Vintage Textile uses the term. Augusta Auctions sells them in lots of three in every sale that includes 1900s garments.
Those are NOT tea gowns (well, more precisely, they were never called tea gowns in any era in which this style of dress was fashionable). Or tea dresses.
Tea gowns is a specific period term that refers to a a totally different kind of garment. This is a tea gown:

Tea gown with front panel of Indian embroidery, ca. 1900, House of Rouff (designer), collection of the V&A
As is this:

Poiret tea gown, Spring 1913. Sold at the Doyle couture auction, November 1999.
And this.
Note how different those examples are from the ones on all the sales sites? That’s because they are totally different styles of garment.
Tea gowns were made of rich, heavy fabrics, often in colours, and usually featured elaborate, trailing sleeves. You can read more about them here.
In contrast, the dresses called tea gowns by modern sellers are made in very lightweight, delicate fabrics, almost always in white. Their sleeves follow the fashionable silhouette for day sleeves of their era.
It’s a historical mis-nomer that annoys me to no end, because, by using a name that referred to a completely unique and distinct garment for the frothy white dresses, it creates confusion about what both types of garments were, what they were used for, who wore them and when, and why each was named each.
So, if all those white dresses with the lace and tucks weren’t tea gowns, what were they called in-period? Lingerie dresses. Or lingerie frocks.

An ad for Bella Hesse garments, including a lingerie dress, featured in the June 1910 Ladies Home Journal magazine

Lingerie dresses featured in the catalogue for the National Cloak & Suit Company, Lingerie Dresses, 1908
Lingerie Frocks
Lingerie dresses were lightweight dresses, usually in white or an off-white shade, featuring pintucks, inset lace, tone-on-tone embroidery, and other delicate detailing, usually worn as summer wear in the late 19th and first quarter of the 20th century. They were usually made of cotton, and slightly less frequently in linen, with more expensive versions were made in silk. They were primarily worn by younger women.

Dress, circa 1912, maker unknown. Gift of Mrs E Hofma, 1985. CC BY-NC-ND 4.0. Te Papa PC003341
They are called ‘lingerie dresses’ or ‘lingerie frocks’ because the materials used (cotton and light laces) and embellishment techniques (inset lace, faggoting, pintucks) were originally used for petticoats, chemises, and other forms of lingerie.

Dress, circa 1912, maker unknown. Gift of Mrs E Hofma, 1985. CC BY-NC-ND 4.0. Te Papa PC003341
‘Lingerie blouses’ ‘Lingerie waists’ and ‘lingerie skirts’ are blouses and skirts made of lightweight, light-coloured fabrics, featuring the same embellishment techniques. Waists were slightly more elaborate than blouses, and usually featured a supportive under-lining, though period catalogues and advertisements sometimes use the words interchangeably.
Suitable fabrics for lingerie dresses/blouses/skirts were: batiste, voile, crepe, handkerchief linen, embroidered swiss (aka dotted swiss), dimity & lawn.
Lingerie dresses were primarily used for daytime wear, and though they were also acceptable informal evening wear in summer, and were particularly suited to hot weather. Simple versions might be worn around the house, more elaborate ones were appropriate for all but the most formal daytime events.

Lingerie dress patterns featured in the June 1910 Ladies Home Journal magazine

Lingerie dress patterns featured in the June 1910 Ladies Home Journal magazine
Lingerie dresses were originally intended as a fancier form of ‘wash dress’ or ‘tub frock’: garments made of materials that could, with care, be washed at home, without special equipment, without damaging them. The relative cheapness of cotton fabrics, and machine-made lace, along with their increased durability, made the dresses both economical and practical. While we might think white fabric was just asking for stains, it had the advantage over coloured fabrics, which were prone to fading, and might not be colourfast in the wash.
While the dresses were originally intended to be relatively easy care, more elaborate versions, in fancier materials, soon became available, and these were not washable.

Fabrics for making lingerie frocks & other garments, featured in the June 1910 Ladies Home Journal magazine
Standard wash frocks are different than lingerie dresses in the amount of trims and applications, and in the weight of materials: wash frocks were simpler, and of more robust fabrics. Whether washable or not, lingerie dresses had more cachet than a standard wash frock. A wash frock was worn around the house as everyday wear: elaborate lingerie dresses were suitable for graduation and confirmation wear.

Lingerie dresses for misses, National Cloak and Suit Company, 1908

Lingerie dresses for misses, National Cloak and Suit Company, 1908
As they were both comfortable for hot weather, and formal enough to suit more elaborate occasions, lingerie dresses formed an essential piece in the wardrobe of any young lady of the Edwardian era who aspired to be well dressed. Lingerie blouses were also essential, instantly turning a simple skirt into a much more formal outfit. Wardrobe guides recommended that a girl own at least one of each the following items of outerwear:
“Middy blouse, cotton, linen or silk shirt, lingerie blouse, cotton and woolen skirts, cotton wash dress, lingerie dress, wool dress for school or street, silk dress for informal occasions, party or evening gown of cotton or silk”

Lingerie waist patterns featured in the June 1910 Ladies Home Journal magazine

Lingerie waist patterns featured in the June 1910 Ladies Home Journal magazine
At the height of their popularity, it was possible to buy length of pre-embroidered fabric, and coordinating laces specifically to make lingerie dresses. Matching embellishments was by no-means a necessity though: Edwardian dressmakers, and even Edwardian couturiers, happily mixed and matched types, and even shades, of lace on all sorts of garments, as well as other embellishments, including lingerie dresses.
Not everyone was a fan of lingerie dresses. The July 1909 Ladies Home Journal called them “a mass of poor embroidery and objectionable cheap lace”

Ladies Home Journal, July 1909 contrasting a day dress in good taste, and a lingerie dress in bad taste
Dresses showing all the typical characteristics of a lingerie dress (light fabrics in light colours, lace insertion) are seen from about 1895 onwards, and were extremely popular by 1900. However, it took a while for a name to be applied to the style, and to gain widespread popularity. The term ‘lingerie dress’ (or blouse) was in widespread use in both the US and UK by 1905, and reached its height of popularity in clothing catalogues, fashion magazines, fashion columns, and sewing patterns between 1908 and 1916.
While their popularity was waning in the late ‘teens and into the 1920s, lingerie dresses continued to be made, worn, and mentioned in fashion columns well into the 1920s. Similar styles are seen in blouses into the 1930s.
Alas, I do not think my terminology point is going to cure the internet of calling lingerie dresses ‘tea gowns’ – the term is too firmly entrenched, and is probably here to stay.
But at least a few more people who are making a recreation of this style of garment, or writing a book set in the era, or a reading a book written in the era will know what to call their garment, or what was meant in the book.
And if you are selling a garment of this style, well, I don’t entirely blame you for still using ‘tea gown’ to make sure you get the hits. Hopefully you can find a way to slip in the right name too, though, and help spread the [right] word 
In short:
Lingerie dresses and lingerie blouses are garments made from lightweight cotton, linen and silk fabrics worn as both day and informal evening wear in hot climates from 1895-1935, but most popular from 1900-1925. They feature tucks, embroidery, and lace insertion techniques originally primarily seen in undergarments: hence their name.

Lingerie dresses featured in the catalogue for the National Cloak & Suit Company, Lingerie Dresses, 1908
You can see more examples of lingerie dresses on my pinterest board, and some 1915 & 16 example from the Pictoral Review here.
References:
Baldt, Laura Irene. Clothing for women; selection, design, construction; a practical manual for school and home. Philadelphia: Lippincott. 1919
Complete Etiquette for Ladies & Gentlemen: A Guide to the Observances of Good Society. London: Ward Lock & Co. circa 1920.
Darnell, Paula Jean. Victorian to Vamp: Women’s Clothing 1900-1929. Reno, NV : Fabric Fancies. 2000
Fales, Jane. Dressmaking: A manual for schools and colleges. New York: Charles Schribner’s Sons. 1917.
Kemper, Rachel H. Costume. New York : Newsweek Books. 1977
Ladies Home Journal, July 1909
National Cloak & Suit Co. New York. Spring-Summer 1908
Tortora, Phyllis G. Dress, Fashion and Technology: From Prehistory to the Present. London: Bloomsbury Press. 2015
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