In a sigmoid shape, which is a shape that looks like the letter 'S'.
The word sigmoidally is used in math and science to describe a certain kind of shape.
Examples:
The snake moved sigmoidally through the grass.
The river curved sigmoidally around the bend.
The road goes sigmoidally up the hill.
The hose was twisted sigmoidally like a snake.
The roller coaster track twisted sigmoidally through the park.
The tree grew sigmoidally, curving back and forth.