What term describes the stretching of an object into a long strand by a black hole’s tidal forces?

The stretching of an object into a long strand by a black hole’s tidal forces is called spaghettification.

Tidal forces arise because gravity is stronger on the side of an object closer to the black hole than on the side farther away. That difference pulls the object lengthwise while compressing it in other directions. For a person or spacecraft, the result would be extreme stretching and destruction.

The effect depends on the black hole’s mass and the object’s distance. A small stellar-mass black hole has a steep gravitational gradient near its horizon, so spaghettification could occur before crossing it. At a supermassive black hole, the gradient at the horizon can be much weaker, allowing an astronaut to cross the horizon before being torn apart. The eventual outcome inside remains unavoidable once the horizon is crossed.