n.
〈音〉（五线谱的）加线

[ noun ]
a short line; a notation for extending the range above or below the staff
<noun.communication>

Leger \Leg"er\, a. [F. l['e]ger, fr. LL. (assumed) leviarius,
fr. L. levis light in weight. See {Levity}.]
Light; slender; slim; trivial. [Obs. except in special
phrases.] --Bacon.

{Leger line} (Mus.), a line added above or below the staff to
extend its compass; -- called also {added line}.