Oboe da caccia
Definition and background:
A baroque instrument of the oboe family. It has an alto / tenor range pitched a fifth below the oboe. The English horn usually takes the place of the oboe da caccia in the modern orchestra.
For more information on the music term "Oboe da caccia" check out these other resources:
Wikipedia - Glossary of Musical Terminology
Virginia Tech Multimedia Music Dictionary
ORB -- Medieval Music Glossary