sag

from The American Heritage® Dictionary of the English Language, 5th Edition.

• intransitive verb To sink, droop, or settle from pressure or weight.
• intransitive verb To lose vigor, firmness, or resilience.
• intransitive verb To decline, as in value or price.
• intransitive verb Nautical To drift to leeward.
• intransitive verb To wear one's pants with the waist below the hips, so that one's underwear is visible.
• intransitive verb To cause to sag.
• noun The act or an instance of sagging.
• noun The degree or extent to which something sags.
• noun A sagging or drooping part or area.
• noun A sunken area of land; a depression.
• noun A sagging area; a depression.
• noun A decline, as in monetary value.
• noun Nautical A drift to leeward.

from The Century Dictionary.

• noun A bending or drooping, as of a rope that is fastened at its extremities, or of a surface; droop.
• To droop, especially in the middle; settle or sink through weakness or lack of support.
• Hence To yield under the pressure of care, difficulties, trouble, doubt, or the like; be depressed.
• To go about in a careless, slovenly manner or state; slouch.
• Nautical, to incline to the leeward; make lee-way.
• To cause to droop or bend in the middle, as by an excessive load or burden: opposed to hog.
• Heavy; loaded; weighed down.
• noun In railroad construction, a depression in the grade of a road; the meeting of a down grade with an up grade. An abrupt sag is objectionable, owing to the varying strains upon the cars of a train passing it, the cars on the up grade being pulled apart and those on the down grade being pressed together, the strains being reversed as each car passes the lowest point of the sag.
• noun A depression in a crest-line or divide.

from the GNU version of the Collaborative International Dictionary of English.

• transitive verb To cause to bend or give way; to load.
• intransitive verb To sink, in the middle, by its weight or under applied pressure, below a horizontal line or plane; ; hence, to lean, give way, or settle from a vertical position.
• intransitive verb rare Fig.: To lose firmness or elasticity; 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.
• intransitive verb To loiter in walking; to idle along; to drag or droop heavily.
• intransitive verb (Naut.) to make much leeway by reason of the wind, sea, or current; to drift to leeward; -- said of a vessel.
• noun State of sinking or bending; sagging.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The state of sinking or bending; sagging.
• noun The difference in elevation of a wire, cable, chain or rope suspended between two consecutive points.
• noun The difference height or depth between the vertex and the rim of a curved surface, specifically used for optical elements such as a mirror or lens.
• verb To sink, in the middle, by its weight or under applied pressure, below a horizontal line or plane; as, a line or cable supported by its ends sags, though tightly drawn; the floor of a room sags; hence, to lean, give way, or settle from a vertical position; as, a building may sag one way or another; a door sags on its hinges.
• verb figuratively 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.
• verb To loiter in walking; to idle along; to drag or droop heavily.
• verb transitive To cause to bend or give way; to load.
• verb informal To wear one's trousers so that their top is well below the waist.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• verb cause to sag
• noun a shape that sags
• verb droop, sink, or settle from or as if from pressure or loss of tautness