diagram

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

• noun A plan, sketch, drawing, or outline designed to demonstrate or explain how something works or to clarify the relationship between the parts of a whole.
• noun Mathematics A graphic representation of an algebraic or geometric relationship.
• noun A chart or graph.
• transitive verb To indicate or represent by or as if by a diagram.

from The Century Dictionary.

• To draw or put into the form of a diagram; make a diagram of.
• noun In geometry, a drawing or scheme delineated for the purpose of demonstrating the properties of any figure by observations on the geometrical relations of its parts.
• noun An illustrative figure giving only the outlines or a general scheme (not an exact representation) of the object; a figure for ascertaining or exhibiting certain relations between objects under discussion by means of analogous relations between the parts of the figure.
• noun In old music, a table representing all the sounds of the system; a musical scale.
• noun A diagram in which the accelerations of particles are represented in magnitude and direction by lines drawn from points showing the positions of those particles.
• noun A diagram in which the displacements of particles are represented in magnitude and direction by lines drawn from points showing the positions of those particles.

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

• transitive verb To put into the form of a diagram.
• noun (Geom.) A figure or drawing made to illustrate a statement, or facilitate a demonstration; a plan.
• noun Any simple drawing made for mathematical or scientific purposes, or to assist a verbal explanation which refers to it; a mechanical drawing, as distinguished from an artistical one.
• noun (Steam Engine) See Indicator card, under indicator

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

• noun A plan, drawing, sketch or outline to show how something works, or show the relationships between the parts of a whole.
• noun A graph or chart.
• noun category theory A functor from an index category to another category. The objects and morphisms of the index category need not have any internal substance, but rather merely outline the connective structure of at least some part of the diagram's codomain. If the index category is J and the codomain is C, then the diagram is said to be "of type J in C".
• verb transitive To represent or indicate something using a diagram.

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

• noun a drawing intended to explain how something works; a drawing showing the relation between the parts
• verb make a schematic or technical drawing of that shows interactions among variables or how something is constructed