"single-reeded tubular woodwind instrument with a bell mouth," 1768, from French clarinette (18c.), diminutive of clarine "little bell" (16c.), noun use of fem. of adjective clarin (which also was used as a noun, "trumpet, clarion"), from clair, cler, from Latin clarus (see clear (adj.)). Alternative form clarionet is attested from 1784.
The instrument, a modification of the medieval shawm, is said to have been invented c. 1700 by J.C. Denner of Nuremberg, Germany, and was a recognized orchestral instrument from c. 1775. The ease of playing it increased greatly with a design improvement from 1843 based on Boehm's flute.
After the hautboy came the clarinet. This instrument astonished every beholder, not so much, perhaps, on account of its sound, as its machinery. One that could manage the keys of a clarinet, forty five years ago, so as to play a tune, was one of the wonders of the age. Children of all ages would crowd around the performer, and wonder and admire when the keys were moved. [Nathaniel D. Gould, "Church Music in America," Boston, 1853]
German Clarinet, Swedish klarinett, Italian clarinetto, etc. all are from French. Related: Clarinettist.