Krummhorn is a term used to refer to a musical instrument that resembles a double reed instrument with a curved tube. This type of instrument is commonly used in medieval music and is known to produce a loud, piercing sound. However, the term krummhorn is one that is not frequently used, and some musicians may opt to substitute it with more commonly used terms. Some synonyms for krummhorn are cornemuse, curtal, or crumhorn. These terms are all used to refer to similar instruments, and their use may depend on individual preference or the specific musical genre being performed.