Basement and Rock-bottom

Basement noun - A room or set of rooms below the surface of the ground.

Rock-bottom and basement are semantically related In some cases you can use "Rock-bottom" instead an adjective "Basement".

Rock-bottom adjective - Of, relating to, or located at the bottom.

Basement and rock-bottom are semantically related in bottom topic. Sometimes you can use "Basement" instead an adjective phrase "Rock-bottom", if it concerns topics such as lowest.