krummhorn

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A wind instrument of the Renaissance with a curving tube and a double reed.

Century Dictionary and Cyclopedia

1. n. A medieval musical instrument of the clarinet class, having a curved tube and a melancholy tone.
2. n. In organ-building, a reed-stop with short, slender metal pipes, and a tone like that of the clarinet. Also called clarinet-stop, cromorna, and corruptly cremona.

Wiktionary

1. n. a mediaeval and Renaissance wind instrument
2. n. a stop on an organ

GNU Webster's 1913

1. n. A reed instrument of music of the cornet kind, now obsolete (see cornet, 1, a.).
2. n. A reed stop in the organ; -- sometimes called cremona.

WordNet 3.0

1. n. a Renaissance woodwind with a double reed and a curving tube (crooked horn)