CLEF
clef
(noun) a musical notation written on a staff indicating the pitch of the notes following it
Source: WordNet® 3.1
Etymology
Noun
clef (plural clefs)
A symbol found on a musical staff that indicates the pitches represented by the lines and the spaces on the staff
Source: Wiktionary
Clef, n. Etym: [F. clef key, a key in music, fr. L. clavis key. See
Clavicle.] (Mus.)
Definition: A character used in musical notation to determine the position
and pitch of the scale as represented on the staff.
Note: The clefs are three in number, called the C, F, and G clefs,
and are probably corruptions or modifications of these letters. They
indicate that the letters of absolute pitch belonging to the lines
upon which they are placed, are respectively C, F, and G. The F or
bass clef, and the G or treble clef, are fixed in their positions
upon the staff. The C clef may have three positions. It may be placed
upon the first or lower line of the staff, in which case it is called
soprano clef, upon the third line, in which case it called alto clef,
or upon the fourth line, in which case tenor clef. It rarely or never
is placed upon the second line, except in ancient music. See other
forms of C clef under C, 2. Alto clef, Bass clef. See under Alto,
Bass.
Source: Webster’s Unabridged Dictionary 1913 Edition