density

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The quality or condition of being dense.
2. n. The quantity of something per unit measure, especially per unit length, area, or volume.
3. n. The mass per unit volume of a substance under specified conditions of pressure and temperature.
4. n. Computer Science The number of units of useful information contained within a linear dimension.
5. n. The number of individuals, such as inhabitants or housing units, per unit of area.
6. n. The degree of optical opacity of a medium or material, as of a photographic negative.
7. n. Thickness of consistency; impenetrability.
8. n. Complexity of structure or content.
9. n. Stupidity; dullness.

Century Dictionary and Cyclopedia

1. n. The quality of being dense, close, or compact; closeness of constituent parts; compactness, actual or relative.
2. n. The mass or amount of matter per unit of bulk. The mass is the ratio of the living force or double the energy of motion to the square of the velocity. Experiments made by Newton upon the effect of attaching masses of different materials to pendulums have shown that the weights of bodies are precisely proportionate to their masses; consequently, the density is measured by the specific gravity, or the weight of a unit bulk. The unit of density is generally taken as that of water at its temperature of maximum density (4° C., 39° F.) and under ordinary pressure. Inasmuch as the gram was intended to be, and within the limits of the probable error of the best observations actually is, the mass of one cubic centimeter of water under these conditions, it is follows that the density as ordinarily expressed is, as closely as possible, the number of grams in one cubic centimeter of the particular kind of matter in question. The following table show the density of several important substances: iridium, 22.4; platinum, 21.4; gold, 19.3; liquid mercury, 13.6; lead, 11.3; silver, 10.5; copper, 8.9; nickel, 8.7; iron, 7.8; tin, 7.3; zinc, 7.2; the earth, 5.6; solution of iodides of mercury and potassium, 3.2; diamond, 3.5; rock, about 2.7; aluminium, 2.6; sulphur, 2.0; magnesium, 1.7; the human body, 1.1; india-rubber, 1.0; alcohol, 0.8; ether, 0.7; lithium, 0.6; vapor of iodide of arsenic, 1.02; air, 0.0013; aqueous vapor, 0.0008; hydrogen, 0.00009. See specific gravity, under gravity.
3. n. In electricity, the quantity of electricity per unit of volume at a point in space, or the quantity of electricity per unit of area at a point on a surface.
4. n. In photography, opacity of the developed film of a negative.

Wiktionary

1. n. physics A measure of the amount of matter contained by a given volume.
2. n. The ratio of one quantity to that of another quantity.
3. n. The probability that an event will occur, as a function of some observed variable.

GNU Webster's 1913

1. n. The quality of being dense, close, or thick; compactness; -- opposed to rarity.
2. n. (Physics) The ratio of mass, or quantity of matter, to bulk or volume, esp. as compared with the mass and volume of a portion of some substance used as a standard.
3. n. (Photog.) Depth of shade.

WordNet 3.0

1. n. the amount per unit size
2. n. the spatial property of being crowded together