"opening in a wall," especially a space between two columns, late 14c. from Old French baee "opening, hole, gulf," noun use of fem. past participle of bayer "to gape, yawn," from Medieval Latin batare "gape," perhaps of imitative origin. Meaning "compartment for storage: is from 1550s. Somewhat confused with bay (n.1) "inlet of the sea," it is the bay in sick-bay and bay window (early 15c.).
فاصله یا گشودگی بین عناصر عمودی مکرر، مانند فواصل مکرر بین سه یا چند ستون، پایه، جرز، یا روزن (opening)های مشابه و مکرر.
«دهانه (۱)» (span) مربوط به سازه و هندسه و اندازه است؛ اما «دهانه (۲)» فاصلهای بصری است و مکرر بودن آن مهم است.