element

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

• noun A fundamental, essential, or irreducible constituent of a composite entity.
• noun The basic assumptions or principles of a subject.
• noun A member of a set.
• noun A point, line, or plane.
• noun A part of a geometric configuration, such as an angle in a triangle.
• noun The generatrix of a geometric figure.
• noun Any of the terms in the rectangular array of terms that constitute a matrix or determinant.
• noun Chemistry & Physics A substance composed of atoms having an identical number of protons in each nucleus. Elements cannot be reduced to simpler substances by normal chemical means. cross-reference: Periodic Table (pages 131X–131X).
• noun One of four substances, earth, air, fire, or water, formerly regarded as a fundamental constituent of the universe.
• noun Electricity The resistance wire in an electrical appliance such as a heater or an oven.
• noun The forces that constitute the weather, especially severe or inclement weather.
• noun An environment naturally suited to or associated with an individual.
• noun A distinct group within a larger community.
• noun A part of a military force, especially.
• noun A ground unit in an air force comparable to a platoon.
• noun A unit of an air force equal to two or three aircraft.
• noun The bread and wine of the Eucharist.

from The Century Dictionary.

• To compound of elements or first principles.
• To constitute; form from elements; compose; enter into the constitution of.
• noun That of which anything is in part compounded, which exists in it, and which is itself not decomposable into parts of different kinds; a fundamental or ultimate part or principle; hence, in general, any component part; any constituent part or principle.
• noun Specifically— An ingredient, especially of the temperament.
• noun plural The rudimentary principles of any science: as, Euclid's “Elements” (Gr. στοιχει%148α), a work setting forth in an orderly and logical way the simple and fundamental propositions of geometry.
• noun In geometry, one of the points, lines, or planes, or other geometrical forms, by which a figure or geometrical construction is made up. “Space may be considered as a geometrical figure whose elements are either points or planes. Taking the points as elements, the straight lines of space are so many ranges, and the planes of space so many planes of points. If, on the other hand, the planes are considered as elements, the straight lines of space are the axes of so many axial pencils, and points of space are centers of so many sheaves of planes” (Cremona, Geom., tr. by Leuesdorff, § 31).
• noun In mathematics, one of a number of objects arranged in a symmetrical or regular figure. The elements of a determinant are the quantities arranged in a square block or matrix, the sum of whose products forms the determinant.
• noun In astronomy, one of the quantities necessary to be known in calculating the place of a planet (perhaps because the planets were called elements). They are six, namely, the longitude of the ascending node, the inclination of the orbit to the ecliptic, the longitude of the perihelion, the mean distance from the sun, the mean longitude at any epoch, and the eccentricity.
• noun A datum required for the solution of any problem.
• noun plural The bread and wine used in the eucharist: distinctively called communion elements.
• noun In biology, one of the primary or embryological parts composing the body of an animal, or of the pieces which have united to form any part. Thus, the thorax of an insect is composed of three principal elements or rings, the epicranium is formed of several elements or pieces which are soldered together, etc.
• noun In electricity, a voltaic cell. See cell.
• noun One of the four things, fire, water, earth, and air (to which ether was added as a fifth element), falsely regarded by the ancients as the constituents of which all things are composed.
• noun A kind of matter undecomposable into other kinds.
• noun There are a number of other bodies which have been named as elements (as phillipium, norwegium, etc.), whose properties have, however, not yet been sufficiently investigated and defined to warrant their inclusion in the list.
• noun The proper or natural environment of anything; that in which something exists; hence, the sphere of experience of a person; the class of persons with whom one naturally associates, or the sphere of life with which one is familiar: as, he is out of his element.

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

• transitive verb obsolete To compound of elements or first principles.
• transitive verb To constitute; to make up with elements.
• noun One of the simplest or essential parts or principles of which anything consists, or upon which the constitution or fundamental powers of anything are based.
• noun One of the ultimate, undecomposable constituents of any kind of matter. Specifically: (Chem.) A substance which cannot be decomposed into different kinds of matter by any means at present employed.
• noun One of the ultimate parts which are variously combined in anything; ; hence, also, a simple portion of that which is complex, as a shaft, lever, wheel, or any simple part in a machine; one of the essential ingredients of any mixture; a constituent part.
• noun One out of several parts combined in a system of aggregation, when each is of the nature of the whole.
• noun (Anat.) One of the smallest natural divisions of the organism, as a blood corpuscle, a muscular fiber.
• noun (Biol.) One of the simplest essential parts, more commonly called cells, of which animal and vegetable organisms, or their tissues and organs, are composed.
• noun An infinitesimal part of anything of the same nature as the entire magnitude considered. In the calculus, element is sometimes used as synonymous with differential.
• noun Sometimes a curve, or surface, or volume is considered as described by a moving point, or curve, or surface, the latter being at any instant called an element of the former.
• noun One of the terms in an algebraic expression.
• noun One of the necessary data or values upon which a system of calculations depends, or general conclusions are based.