C Clef Definition
    noun
  
 A sign on a staff indicating that C is the note on the third line (alto clef) or on the fourth line (tenor clef)
Webster's New World 
Other Word Forms of C Clef
Noun
Singular:
 C clefPlural:
 c-clefsA sign on a staff indicating that C is the note on the third line (alto clef) or on the fourth line (tenor clef)