Noun
bass staff (plural bass staffs or bass staves)
(music) a staff which starts with a bass clef
In the case of 7-flat key signatures, the final F may occasionally be seen on the second-top line of the bass staff, whereas it would more usually appear below the bottom line. Source: Internet
The A which is the 5th sharp in the sharp signatures may occasionally be notated on the top line of the bass staff, whereas it is more usually found in the lowest space on that staff. Source: Internet