backstairs

adjective

1. associated or originating with household servants.
2. secret, underhanded, or scandalous: backstairs gossip.

pl n

1. a secondary staircase in a house, esp one originally for the use of servants

adjective Also: backstair

2. underhandbackstairs gossip

“stairs at the back of a structure,” 1650s, from back (adj.) + stairs (see stair). Figurative use is attested earlier (1640s).