section

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

• noun One of several components; a piece.
• noun A subdivision of a written work.
• noun Law A distinct portion or provision of a legal code or set of laws, often establishing a particular legal requirement.
• noun A distinct portion of a newspaper.
• noun A distinct area of a town, county, or country.
• noun A land unit equal to one square mile (2.59 square kilometers), 640 acres, or ¹/₃₆ of a township.
• noun The act or process of separating or cutting, especially the surgical cutting or dividing of tissue.
• noun A thin slice, as of tissue, suitable for microscopic examination.
• noun A segment of a fruit, especially a citrus fruit.
• noun Representation of a solid object as it would appear if cut by an intersecting plane, so that the internal structure is displayed.
• noun Music A group of instruments or voices in the same class considered as a division of a band, orchestra, or choir.
• noun A class or discussion group of students taking the same course.
• noun A portion of railroad track maintained by a single crew.
• noun An area in a train's sleeping car containing an upper and lower berth.
• noun An army tactical unit smaller than a platoon and larger than a squad.
• noun A unit of vessels or aircraft within a division of armed forces.
• noun One of two or more vehicles, such as a bus or train, given the same route and schedule, often used to carry extra passengers.
• noun The character (§) used in printing to mark the beginning of a section.
• noun This character used as the fourth in a series of reference marks for footnotes.
• noun Informal A cesarean section.
• transitive verb To separate or divide into parts.
• transitive verb To cut or divide (tissue) surgically.
• transitive verb To shade or crosshatch (part of a drawing) to indicate sections.
• transitive verb Informal To perform a cesarean section on.

from The Century Dictionary.

• To make a section of; divide into sections, as a ship; cut or reduce to the degree of thinness required for study with the microscope.
• To cut sections; divide into sections.
• noun In petrography, in the quantitative classification of igneous rocks (see rock), a subdivision of any of the taxonomic divisions from class to subgrad. It is used wherever it is considered necessary to introduce a further subdivision.
• noun In geology, a group of several related stages, usually of the same kind of sedimentary rock; a series or formation.
• noun In function-theory, a line in the plane of the variable of a function upon crossing which the function abruptly changes its value.
• noun The act of cutting or dividing; separation by cutting: as, the section of one plane by another.
• noun A part cut or separated, or regarded as separated, from the rest; a division; a portion.
• noun One of the squares, each containing 640 acres, into which the public lands of the United States are divided; the thirty-sixth part of a township.
• noun A certain proportion of a battalion or company told off for military movements and evolutions.
• noun In mech., any part of a machine that can be readily detached from the other parts, as one of the knives of a mower.
• noun A division in a sleeping-car, including two seats facing each other, and designed to be made into two sleeping-berths. A double section takes in four seats, two on each side of the car.
• noun In bookbinding, the leaves of an intended book that are folded together to make one gathering and to prepare them for sewing.
• noun In printing, that part of a printed sheet of book-work which has to be cut off from the full sheet and separately folded and sewed. On paper of ordinary thickness, the section is usually of eight leaves or sixteen pages; on thick paper, the section is often of four leaves or eight pages.
• noun The curve of intersection of two surfaces.
• noun A representation of an object as it would appear if cut by any intersecting plane, showing the internal structure; a diagram or picture showing what would appear were a part cut off by a plane supposed to pass through an object, as a building, a machine, a biological structure, or a succession of strata.
• noun A thin slice of an organic or inorganic substance cut off, as for microscopic examination.
• noun In zoology, a classificatory group of no fixed grade or taxonomic rank; a division, series, or group of animals: used, like group, differently by different authors.
• noun In botany, a group of species subordinate to a genus: nearly the same as subgenus (which see).
• noun In fortification, the outline of a cut made at any angle to the principal lines other than a right angle.
• noun The sign §, used either as a mark of reference to a foot-note, or , prefixed to consecutive numerals, to indicate divisions of subdivisions of a book.
• noun = Syn.2. Division, Piece, etc. See part, n.

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

• noun The act of cutting, or separation by cutting.
• noun A part separated from something; a division; a portion; a slice.