¦ adjective
1. allowing access, passage, or view; not closed, fastened, or restricted.
2. exposed to the air or to view or attack; not covered or protected: an open boat.
(of land) not covered with buildings or trees.
(open to) vulnerable or subject to.
(of a town or city) officially declared to be undefended, and so immune under international law from bombardment.
3. spread out or unfolded.
(of a book) with the covers parted and able to be read.
4. admitting customers or visitors; available for business.
freely available or accessible.
(of an offer or opportunity) still available.
5. frank and communicative.
not concealed; manifest.
welcoming public discussion, criticism, and enquiry: open government.
6. (of a matter) not finally settled.
(often open to) receptive to new ideas.
(open to) admitting of; making possible.
7. Music (of a string) allowed to vibrate along its whole length.
(of a pipe) unstopped at each end.
8. Phonetics (of a vowel) produced with a relatively wide opening of the mouth and the tongue kept low.
(of a syllable) ending in a vowel.
9. (of an electric circuit) having a break in the conducting path.
10. (of a fabric) loosely knitted or woven.
¦ verb
1. move (a door, window, etc.) so that it is open.
undo or remove the cover or fastening of.
(open on to/into) (of a door, window, etc.) give access to.
2. unfold or be unfolded; spread out.
part the covers of (a book) to read it.
(of a prospect) extend into view.
3. make or become open for customers or visitors.
ceremonially declare (a building, road, etc.) to be completed and ready for use.
4. formally begin or establish.
(open up or open fire) begin shooting.
(of a counsel in a law court) make a preliminary statement in (a case) before calling witnesses.
Bridge make (the first bid) in the auction.
5. make available or more widely known.
(open out/up) become more communicative or confiding.
6. break the conducting path of (an electric circuit).
¦ noun
1. (the open) outdoors or in the countryside.
(usu. in phr. in/into the open) a lack of concealment or secrecy.
2. (Open) a championship or competition with no restrictions on who may compete.
3. an accidental break in the conducting path for an electric current.
Phrases
the open air a free or unenclosed space outdoors.
in open court in a court of law, before the judge and the public.
open-and-shut (of a case or argument) admitting no doubt or dispute; straightforward.
Derivatives
openable adjective
openness noun
Origin
OE
open (adjective),
openian (v.), of Gmc origin, from the root of the adverb
up.