This lexicon is a selective list of common urban design terms, used in the book Urban Design Reclaimed (by E. Talen, Planners Press, 2009). There are three main sources for the definitions: SC: Smart Code (http://smartcodecentral.com/); PPS: Project for Public Spaces (http://www.pps.org/); and PD: A Planners Dictionary (https://www.planning.org/).

  Accessory Unit: An apartment sharing owner­ship and utility connections with a principal building. SC

Arcade: A private frontage usually for retail use wherein the facade is a colonnade supporting habitable space that overlaps the sidewalk, while the facade at sidewalk level remains at the frontage line. SC
  Atrium: A ground-level area designed for pedestrians that meets the following conditions: (a) has at least one entrance connecting to a public street, plaza, or arcade; (b) is open to the top of the building by means of a vertical open space or light well and is covered by a transparent or translucent material; (c) is open to the public during business hours; (d) has at least 25 percent of its periphery utilized by retail sales, personal services or entertainment activities; and (e) contains facilities for the public, such as benches, flower beds, fountains, etc. PD
  Avenue (AV): a thoroughfare of high vehicular capacity and low to moderate speed, acting as a short distance connector between urban centers, and usually equipped with a landscaped median. SC
  Block: The aggregate of private lots, passages, rear alleys and rear lanes, circumscribed by thoroughfares. SC
  Bollard: Vertical posts used to further reduce the "optical width" of a narrowed street, thereby discouraging speeding. PPS
  Boulevard (BV): A thoroughfare designed for high vehicular capacity and moderate speed, traversing an urbanized area. Boulevards are usually equipped with slip roads buffering sidewalks and buildings. SC
  Bulbout: see curb extension.
  Chicane: Sidewalk extensions that jog from one side of a street to the other to replicate such a circuitous route. PPS
  Choker: Extensions in selected areas – such as at intersections or at mid-block – as opposed to a full sidewalk widening. PPS
  Civic Building: A building operated by not-for-profit organizations dedicated to arts, culture, education, recreation, government, transit, and municipal parking, or for use approved by the legislative body. SC
  Civic Space: An outdoor area dedicated for public use. Civic Space types are defined by the combination of certain physical constants including the relationships among their intended use, their size, their landscaping and their enfronting buildings. SC
  Civic: The term defining not-for-profit organizations dedicated to arts, culture, educa­tion, recreation, government, transit, and municipal parking. SC
  Commercial: The term collectively defining workplace, Office, Retail, and Lodging Functions. SC
  Configuration: The form of a building, based on its massing, Private Frontage, and height. SC
  Corridor: A lineal geographic system incorporating transportation and/or Greenway trajectories. SC
  Courtyard Building: A building that occupies the boundaries of its lot while internally defining one or more private patios. SC
  Curb: The edge of the vehicular pavement that may be raised or flush to a swale. It usually incorporates the drainage system. SC
  Curb extension: A section of sidewalk at an intersection or midblock crossing that reduces the crossing width for pedestrians and that can help reduce traffic speeds.
  Density: The number of dwelling units within a standard measure of land area. SC
  Diverter: These physical barriers redirect traffic heading for a certain street onto a different course, reducing vehicle overload on vulnerable (usually residential) streets overrun by through traffic looking for shortcuts. PPS
  Edgeyard Building: A building that occupies the center of its lot with setbacks on all sides. SC
  Facade: The exterior wall of a building that is set along a frontage line. SC
  Frontage: The area between a building facade and the vehicular lanes, inclusive of its built and planted components. Frontage is divided into Private Frontage and Public Frontage. SC
  Gateway: An entrance corridor that heralds the approach of a new landscape and defines the arrival point as a destination. A point along a roadway at which a motorist or pedestrian gains a sense of having entered the city or a particular part of the city. This impression can be imparted through such things as signs, monuments, landscaping, a change in development character, or a natural feature. PD
  Green: A civic space type for unstructured recreation, spatially defined by landscap­ing rather than building Frontages. SC
  Greenfield: An area that consists of open or wooded land or farmland that has not been previously developed. SC
  Greenway: An open space corridor in largely natural conditions which may include trails for bicycles and pedestrians. SC
  Infill: noun – new development on land that had been previously developed, includ­ing most greyfield and brownfield sites and cleared land within urbanized areas. verb – to develop such areas. SC
  Kiosk: A freestanding structure upon which temporary information and/or posters, notices, and announcements are posted, or a freestanding building with one or more open sides from which commercial activities are conducted. PD
  Live-Work: A mixed use unit consisting of a commercial and residential function. The commercial function may be anywhere in the unit. It is intended to be occupied by a business operator who lives in the same structure that contains the commercial activity or industry. SC
  Lot Line: The boundary that legally and geometrically demarcates a Lot. SC
  Lot Width: The length of the Principal Frontage Line of a Lot. SC
  Lot: A parcel of land accommodating a building or buildings of unified design. The size of a Lot is controlled by its width in order to determine the grain (i.e., fine grain or coarse grain) of the urban fabric. SC
  Median: An area in the approximate center of a city street or state highway that is used to separate the directional flow of traffic, may contain left-turn lanes, and is demarcated by curb and guttering, having painted or thermally applied stripes or other means of distinguishing it from the portion of the roadway used for through traffic. PD
  Mixed Use: Multiple functions within the same building through superimposition or adjacency, or in multiple buildings by adjacency, or at a proximity determined by warrant. SC
  Multigenerational park: Parks that simultaneously provide outdoor physical activities and spaces for toddlers, children, teens, adults and seniors. They include both active (playground) and passive (leisure time) activities, and may include equipment designed for multigenerational use.
  Multi-way boulevard: A street developed as two one-way pavements separated by a median. PD
  Neckdown: see choker.
  Open Space: Land intended to remain undeveloped; it may be for civic space. SC
  Park: A civic space type that is a natural preserve available for unstructured rec­reation. SC
  Parking Structure: A building containing one or more stories of parking above grade. SC
  Path: a pedestrian way traversing a park or rural area, with landscape match­ing the contiguous open space, ideally connecting directly with the urban sidewalk network. SC
  Pedestrian Shed: An area that is centered on a common destination. Its size is related to average walking distances for the applicable community unit type. Pedestrian Sheds are applied to structure communities. A standard pedestrian shed is an average 1/4 mile radius or 1320 feet, about the distance of a five-minute walk at a leisurely pace. SC
  Planter: The element of the public frontage which accommodates street trees, whether continuous or individual. SC
  Play lot: A small area developed especially for preschool or elementary school aged children. It may contain such facilities as sandboxes, slides, teeters, swings, climbing apparatus, and the like. PD
  Plaza: A civic space type designed for civic purposes and commercial activities in the more urban transect zones, generally paved and spatially defined by building frontages. SC
  Pocket park: A small area of open space that is developed and maintained for active or passive recreational use by the residents of a neighborhood or development. A pocket park may include lawn areas, a tot lot or playground, or picnic areas.
  Principal Building: The main building on a lot, usually located toward the frontage. SC
  Private Frontage: The privately held layer between the frontage line and the principal building facade. SC
  Public Frontage: The area between the curb of the vehicular lanes and the front­age line. SC
  Refuge Island: A protected area between traffic lanes providing pedestrians with a safe place to wait for gaps in traffic.
  Right-of-way: A strip of land acquired by reservation, dedication, prescription, or condemnation and intended to be occupied by a street, trail, water line, sanitary sewer, and/or other public utilities or facilities. SC. Alternate definitions: The line determining the street or highway public limit or ownership. A public or private area that allows for the passage of people or goods. Right-of- way includes passageways such as freeways, streets, bike paths, alleys, and walkways. A public right-of-way is a right-of-way that is dedicated or deeded to the public for public use and under the control of a public agency. PD
  Road: A local, rural and suburban thoroughfare of low-to-moderate vehicular speed and capacity. This type is allocated to the more rural transect zones (t1-t3). SC
  Roundabout: A raised island that is usually landscaped and located at the intersection of two streets used to reduce traffic speeds and accidents without diverting traffic onto adjacent residential streets. PD
  Rowhouse: A single-family dwelling that shares a party wall with another of the same type and occupies the full frontage line. SC
  Setback: The area of a lot measured from the lot line to a building facade or elevation that is maintained clear of permanent structures, with the exception of encroachments. SC
  Sidewalk: the paved section of the public frontage dedicated exclusively to pedes­trian activity. SC
  Sidewalk extension: see curb extension.
  Square: A civic space type designed for unstructured recreation and civic purposes, spatially defined by building frontages and consisting of paths, lawns and trees, formally disposed. SC
  Street: A local urban thoroughfare of low speed and capacity. SC
  Terminated Vista: a location at the axial conclusion of a thoroughfare. SC
  Thoroughfare: A way for use by vehicular and pedestrian traffic and to provide access to lots and open spaces, consisting of vehicular lanes and the public frontage. SC
  Thoroughfare assembly: All the elements that surround and include thoroughfares: ROWs, parking lanes, travel lanes, curb radii, and public frontages (sidewalks, planters, street trees). SC
  Traffic circle: see roundabout.
  Transect Zone (T-zone): One of several areas on a zoning map regulated by the SmartCode. Transect zones are administratively similar to the land use zones in conventional codes, except that in addition to the usual building use, density, height, and setback requirements, other elements of the intended habitat are integrated, including those of the private lot and building and public frontage. SC
  Transect: A cross-section of the environment showing a range of different habitats. The rural-urban Transect of the human environment used in the SmartCode tem­plate is divided into six Transect Zones. These zones describe the physical form and character of a place, according to the Density and intensity of its land use and Urbanism. SC
  Urbanism: Collective term for the condition of a compact, mixed use settlement, including the physical form of its development and its environmental, functional, economic, and sociocultural aspects. SC
  Woonerf: Woonerf is a Dutch word for an area, usually residential, where motorists and other users share the street without boundaries such as lanes and curbs. The term can be translated as "residential yard," reflecting its popularity in the Netherlands where private space is limited. In a woonerf, people on bikes and on foot have access to the whole street, not just sidewalks. Moreover, the street functions as a public living room, where adults gather and children play safely because vehicle speed is kept to a minimum.
  Zoning Map: the official map or maps that are part of the zoning ordinance and delineate the boundaries of individual zones and districts. SC