A definition is an accurate cognitive overlay of a unit of reality; precisely inscribing the boundaries, structurally and qualitatively, as a tracing.
Definitions are the building blocks of clear and precise thinking.
Definitions clarify thought; they enable our comprehension of elusive concepts; they inscribe boundaries and reveal shape and form; and they enable us to compare, arrange and interlock the component parts of a broader picture.
Structure and quality may need defining separately, though they may infer each other.
Different angles of perspectives of the item may require different definitions, and different for both structure and quality. But all definitions should be compatible with each other, providing different views of the same item, as if taking pictures while circumnavigating the item.
Contrast may be used to clarify the boundary between what the item is and what it is not. Contrast is obtained by comparing definitions of both adjacent items and opposing items, and items related in other ways.
Definitions of realities adjacent to each other should intersect precisely, as do the adjacent parts of reality itself.
As well as defining the item’s structure and quality, and its adjacent and opposing items, its function too, can be defined, as can its cause, effect and purpose.
And these definitions being cognitive overlays of reality, are like a felt pen tracings on a windowpane of the objects outside the window.
Descriptions are elaborations / further details of the definition’s interior, and explanations are these too and also refer to its surrounding circumstances and interactive dynamics.