Por·tal n.
 1. A door or gate; hence, a way of entrance or exit, especially one that is grand and imposing.
 Thick with sparkling orient gems
 The portal shone.   --Milton.
    From out the fiery portal of the east.   --Shak.
 2. Arch. (a) The lesser gate, where there are two of different dimensions. (b) Formerly, a small square corner in a room separated from the rest of the apartment by wainscoting, forming a short passage to another apartment. (c) By analogy with the French portail, used by recent writers for the whole architectural composition which surrounds and includes the doorways and porches of a church.
 3. Bridge Building The space, at one end, between opposite trusses when these are terminated by inclined braces.
 4. A prayer book or breviary; a portass. [Obs.]
 Portal bracing Bridge Building, a combination of struts and ties which lie in the plane of the inclined braces at a portal, serving to transfer wind pressure from the upper parts of the trusses to an abutment or pier of the bridge.