Portal Por"tal, n. [OF. portal, F. portail, LL. portale, fr. L. porta a gate. See Port a gate.] 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.