- The spaces between posts, columns, or buttresses in the length of a building, the division in the widths being called aisles. This meaning also applies to overhead vaults (between ribs), in a building using a vaulted structural system. For example, the Gothic architecture period's Chartres Cathedral has a nave (main interior space) that is "seven bays long." Similarly in timber framing a bay is the space between posts in the transverse direction of the building and aisles run longitudinally.
- Where there are no columns or other divisions, and regularly-spaced windows, each window in a wall is counted as a bay. For example Mulberry Fields in Maryland US, a Georgian style building, is described as "5 bay by 2 bay", meaning "5 windows at the front and 2 windows at the sides".
- A recess in a wall, such as a bay window.
- A division of space such as an animal stall, sick bay, or bay platform.
- The space between joists or rafters, a joist bay or rafter bay.
The Japanese ken and Korean kan are both bays themselves and measurements based upon their number and standard placement. Under the Joseon, Koreans were allocated a set number of bays in their residential architecture based upon their class.
- "Bay" Online Etymology Dictionary. http://www.etymonline.com/index.php?allowed_in_frame=0&search=bay&searchmode=none accessed 3/10/2014
- "Bay", n.3. def. 1-6 and "Bay", n.5 def 2. Oxford English Dictionary Second Edition on CD-ROM (v. 4.0) © Oxford University Press 2009