glacier

n. a very large mass of ice that moves slowly down a mountain or across land.

n. a large body of ice which flows under its own mass, typically moving downhill or outward from a centre of accumulation.

“The hikers walked carefully across the surface of the glacier to see the blue ice.”

“Climate scientists are monitoring the rate at which the glacier is retreating, as its melting contributes significantly to rising sea levels.”

n. something that moves or changes very slowly.

n. a figurative reference to an entity, process, or person that moves at an exceptionally slow pace.

“The traffic was moving like a glacier during the morning rush hour.”

“Progress on the new legislation has been moving like a glacier, with committee members debating every minor clause for weeks on end.”

Informal