Lowest and Rock-bottom

Lowest adjective - Being the least in amount, number, or size possible.

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

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

Lowest and rock-bottom are semantically related in bottom topic. You can use "Lowest" instead the phrase "Rock-bottom" as an adjective or a noun.