"The Fashions of the Day, or Time Past and Present, Respectfully dedicated to the Fashionable Editors of La Belle Assemblé, Le Beau Monde &c. &c.", an 1807 caricature engraved by Charles Williams after a drawing by Woodward, which presents an (exaggerated) contrast between "The Year 1740: A Lady's full dress of Bombazeen" (i.e. bombazine or bombasine, a heavy corded fabric) and "The year 1807: A Lady's undress of Bum-be-seen:

Note that "undress" didn't mean anything naughty -- there's a definition of it here.[1] In pursuing his goal of satirizing certain features of contemporary 1807 fashions, the caricaturist did not really draw a fair comparison between the styles of 1740 and 1807, since a young Regency fashionable is juxtaposed here to a sedate middle-aged pre-Regency lady (perhaps in mourning), and such features of mid-18th century dress as tight stiff stays with extremely low necklines were not included (also, the "1740" costume actually seems to be somewhat of a pastiche with 17th century styles).

(Women's fashions of the Empire/Regency weren't always "sensible", but their excesses do seem to be more in accord overall with the spirit of the 21st century than the fashion excesses of most other periods between the 16th century and World War I, which tended to go in for such things as huge hoopskirts and tight corsets...)

Source: http://commons.wikimedia.org/wiki/File:1807-pseudo1740_Fashion-contrast_Bombazine-pun.jpg