The state of sinking or bending; a droop.

The difference in elevation of a wire, cable, chain or rope suspended between two consecutive points.

The difference in height or depth between the vertex and the rim of a curved surface, specifically used for optical elements such as a mirror or lens.

To sink, in the middle, by its weight or under applied pressure, below a horizontal line or plane.

“A line or cable supported by its ends sags, even if it is tightly drawn.”

(by extension) To lean, give way, or settle from a vertical position.

“A building may sag one way or another.”

To lose firmness, elasticity, vigor, or a thriving state; to sink; to droop; to flag; to bend; to yield, as the mind or spirits, under the pressure of care, trouble, doubt, or the like; to be unsettled or unbalanced.