Style is a wonderful word. According to the dictionary, it can mean: 1) manner or type of expression ("which style?"); 2) distinction, excellence, or originality in the manner of expression ("what style!"); 3) fashionability (how "stylish").

When we talk of an "architectural style," we are usually concerned with the first definition above. However, every historic architectural style has become recognized only after first becoming both distinct and fashionable.

Before considering specific architectural styles and their examples in Washington, a categorization of generic architectural elements of style -- the constituent pieces of buildings -- is in order, because architects use most of them to shape buildings and urban spaces regardless of style type.

Think about and look at buildings in the city or in your neighborhood. If you squint slightly while looking, you will lose some of the specific, stylistic detail, but you still will see most of the basic compositional components.

The overall massing or volumetric form may be evident, whether a sigle volume or an aggregation of volumes. Related to the massing is the form of the roof, if visible, and its profile or silhouette against the background of sky, landscape, or other building masses.

You perceive wall surfaces and patterns of openings within them, usually windows or doors; these are among the most important elements susceptible to manipulation for stylistic purposes. Fenestration (the architects' word for window and door patterns in facades) greatly affects comprehension of building mass, scale and type, plus what we experience when inside.

Standing closer to a building, you realize that the individual window openings and the windows themselves contribute significantly to character and style. Designers must consider window types, sizes, proportions, frame and sash details, groupings or subdivisions of glass areas, along with the position of the window plane in relation to the wall face (flush? recessed? projecting?) both inside and outside.

Entrance elements -- walkways, stairs, porches or porticoes, canopies, and principal entry doors -- are integral parts of building massing and wall compositions, although their expression can vary greatly. Some are subtle, others ceremonial.

The column (architects rarely call them posts or pillars) and collections of columns can stand free, form rows or collonades, support roofs or pieces of buildings, mark edges and corners of spaces in the absence of walls, or become part of walls by emerging as pilasters.

Elements that span space horizontally -- lintels, beams, trusses, slabs, arches, vaults, domes -- are found sitting atop walls or columns. Some, like lintels, beams and arches, are generally perceived as two-dimensional, planar elements over openings in walls or between columns. But slabs, vaults and domes are clearly spatial and three-dimensional, as are some trusses. When rows of columns or piers (in effect, very abbreviated walls) or joined and spanned by horizontal elements, they become arcades, loggias, trellises, or galleries.

Building materials, plus color, are still another set of elements through which architects have developed stylistic expressions, Inevitably, every component of the built environment has a color and is made of materials whose visual texture may or may not be revealed and exploited for stylistic effect.

Entering a building, you may see that architectural style is not just an exterior phenomenon. Most of what's outside also can appear inside and be used in the same way. The walls of rooms can be treated just like building facades. And clearly, the organization of a building's interior, especially its floor plan, affects the organization of its exterior. Thus the floor plan and the spaces within a building are subject to manipulation, capable of telegraphing stylistic intent.

Finally come the purely decorative elements, the ornament, the stuff that is optional from a functional and technical point of view. Some have historic origins based on construction necessity and were not always matters of choice. Even as their constructional necessity diminished, their purely decorative role became conventionalized, and architects continued to use and interpret them independent of any technical considerations.

For the most part, decorative motifs are applied at points in buildings where elements cited above either change direction or meet other elements . . . at joints both large and small in scale. A building meeting the ground at its bottom and the sky at its top is perhaps the biggest of these joints.

Corners where walls meet, whether inside or outside, are often subject to ornamental elaboration. Openings in walls for doors and windows -- sills, jambs, and heads -- are one of the architect's favorite set of joints for embellishment. Joints of opportunity occur when columns meet floors (the column base) and spanning elements at their top (the column capital).

Where overhanging roofs, balconies, or bay windows intersect walls, decoration may appear. Sometimes architects decorate unbroken surfaces with inscribed or applied patterns that do not reflect joints between elements. Or they may use construction materials that come in small units -- wood, brick, tile, stone -- to establish decorative surface patterns.

We see friezes, moldings, belt-courses, and facias girdling building volumes or rooms from top through middle to bottom. Moldings and frames encircle openings, often changing from lintel to jamb to sill. Decorative trim may appear where two different elements come together in the same plane, at right angles, or at any other angle for that matter, frequently to conceal rough edges or gaps between dissimilar materials. Brackets of all shapes and sizes may mediate between horizontal and vertical elements while perhaps serving a structural purpose.

Of course, architects sometimes choose as their decorative strategy the minimizing of applied ornament. They rely instead only on the required constructional elements, essential assembly details, and finishes to provide a kind of natural, presumably honest and unpretentious system of self-ornamentation.

If now you were to stop squinting and examine this shopping list of architectural ingredients, you would realize that people rarely analyze buildings this way. Rather, an overall impression or image is conveyed, often very quickly, which you intuitively understand to be a style, even if you don't know its exact name or historical period or the labels for all its parts.

This is not accidental. Most good architecture utilizes dominant themes enhanced and reinforced by sub-themes, secondary analogies and counterpoints. Minor design events that can be viewed separately contribute simultaneously to major events, in turn adding up to one all-encompassing impression of the whole. There is a consistent visual language and vocabulary of expression chosen willfully but thoughtfully by the architect.

Like symphonies with their key signatures, movements, tempos, melodic motifs and orchestration, buildings must be composed and assembled piece by piece over time, yet always with the imprint and memory of a unifying conception, a "big idea." Unlike symphonies, however, buildings are rarely seen in isolation; their composition must acknowledge the physical context in which they stand, be it urban or suburban.

Architects tend to be innovative, searching for new aesthetic ideas, new forms of graphic expression, new visual symphonies. If they invent a new way of making buildings, a new scenario for the whole and its kit of parts . . . if other architects seek to emulate or refine it . . . and if patrons and the public accept it, then a style is born. Even then, it still must exhibit those generic architectural elements familiar to all.

NEXT WEEK: Styles of the 18th and 19th centuries