mechanism

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A machine or mechanical appliance.
2. n. The arrangement of connected parts in a machine.
3. n. A system of parts that operate or interact like those of a machine: the mechanism of the solar system.
4. n. An instrument or a process, physical or mental, by which something is done or comes into being: "The mechanism of oral learning is largely that of continuous repetition” ( T.G.E. Powell).
5. n. A habitual manner of acting to achieve an end.
6. n. Biology The involuntary and consistent response of an organism to a given stimulus.
7. n. Psychology A usually unconscious mental and emotional pattern that shapes behavior in a given situation or environment: a defense mechanism.
8. n. The sequence of steps in a chemical reaction.
9. n. Philosophy The doctrine that all natural phenomena are explicable by material causes and mechanical principles.

Century Dictionary and Cyclopedia

1. n. The structure of a machine, engine, or other contrivance for controlling or utilizing natural forces; the arrangement and relation of parts, or the parts collectively, in any machine, tool, or other contrivance; means of mechanical action; machinery; hence, the structure of anything that is conceived to resemble a machine.
2. n. A mechanical contrivance or agency of any kind; in general, the apparatus, means, or mode by which particular effects are produced or purposes accomplished: as, the mechanism of a musical instrument (the apparatus by means of which the performer acts upon it); the mechanism of a play or of a poem; the mechanism of government.
3. n. Action according to the laws of mechanics; mechanical action.

Wiktionary

1. n. Within a machine or machinery; any mechanical means for the conversion or control of motion, or the transmission or control of power
2. n. Any combination of cams, gears, links, belts, chains and logical mechanical elements
3. n. A group of objects or parts that interact together. (as in Political machine)
4. n. A mental, physical, or chemical process.
5. n. philosophy A theory that all natural phenomena can be explained by physical causes.

GNU Webster's 1913

1. n. The arrangement or relation of the parts of a machine; the parts of a machine, taken collectively; the arrangement or relation of the parts of anything as adapted to produce an effect
2. n. The series of causal relations that operate to produce an effect in any system.
3. n. Mechanical operation or action.
4. n. (Kinematics) An ideal machine; a combination of movable bodies constituting a machine, but considered only with regard to relative movements.

WordNet 3.0

1. n. (philosophy) the philosophical theory that all phenomena can be explained in terms of physical or biological causes
2. n. device consisting of a piece of machinery; has moving parts that perform some function
3. n. a natural object resembling a machine in structure or function
4. n. the atomic process that occurs during a chemical reaction
5. n. the technical aspects of doing something