1899, in reference to the artistic, literary, and decorative styles popular in middle-class, mid-19c. German households. It is from German, a reference to Gottlieb Biedermeier, the name of a fictitious writer of stodgy poems (invented by Ludwig Eichrodt as a satire on bourgeois taste). The term was used in German publications from c. 1870. Also as an adjective, "conventional, bourgeois."
1852, from German umlaut "change of sound," from um "about" (from Proto-Germanic umbi, from PIE root *ambhi- "around") + laut "sound," from Old High German hlut (from Proto-Germanic *hludaz "heard, loud," from suffixed form of PIE root *kleu- "to hear"). Coined 1774 by poet Friedrich Gottlieb Klopstock (1724-1803) but first used in its current sense "modification of vowels" 1819 by linguist Jakob Grimm (1785-1863).
The scribal use of umlaut marks in German began 14c. as the pronunciation of some sounds simplified, to indicate the older ("proper") pronunciation; originally it was a full letter -e- above a -u- (later also added to -a- and -o-).
When the umlauted diphthong came to be pronounced as a single vowel sound ü, the e was then written over the u by many scribes in order to indicate the proper pronunciation of what had become a monophthong. ... Our "umlaut marks" are simply the vestiges of the two broken strokes of the Gothic-script e. [John T. Waterman, "A History of the German Language," University of Washington Press, 1976]