Bass clefs

[Becky]

a sign on a stave (= the five lines on which music is written) that shows that the notes are below middle C (= the C near the middle of a piano keyboard)

[Monty]

in Western music, a sign that shows the fourth line of a staff (= the five lines on which music is written) is the note F below middle C (= the note C near the middle of a piano keyboard)