Open  —adj. 1 not closed, locked, or blocked up; allowing access. 2 unenclosed, unconfined, unobstructed (the open road; open views). 3 a uncovered, bare, exposed (open drain; open wound). B (of a goal etc.) Unprotected, undefended. 4 undisguised, public, manifest (open hostilities). 5 expanded, unfolded, or spread out (had the map open on the table). 6 (of a fabric) not close; with gaps. 7 a frank and communicative. B open-minded. 8 a accessible to visitors or customers; ready for business. B (of a meeting) admitting all, not restricted to members etc. 9 (of a race, competition, scholarship, etc.) Unrestricted as to who may compete. 10 (foll. By to) a willing to receive (is open to offers). B (of a choice, offer, or opportunity) available (three courses open to us). C vulnerable to, allowing of (open to abuse; open to doubt). 11 (of a return ticket) not restricted as to the day of travel. —v. 1 make or become open or more open. 2 (foll. By into, on to, etc.) (of a door, room, etc.) Give access as specified (opened on to a patio). 3 a start, establish, or set going (a business, activity, etc.) (opened a new shop; opened fire). B start (conference opens today). 4 (often foll. By with) start; begin speaking, writing, etc. (show opens with a song; he opened with a joke). 5 ceremonially declare (a building etc.) In use. —n. 1 (prec. By the) a open space, country, or air. B public notice; general attention (esp. Into the open). 2 open championship or competition etc.  open a person's eyes enlighten a person. Open out 1 unfold. 2 develop, expand. 3 become communicative. Open up 1 unlock (premises). 2 make accessible. 3 reveal; bring to notice. 4 accelerate. 5 begin shooting or sounding.  openness n. [old english]