Merriam-Webster Collegiate Dictionary - open

 I. adjective  (~er; ~est)  Etymology: Middle English, from Old English; akin to Old High German offan ~, Old English up up  Date: before 12th century  1. having no enclosing or confining barrier ; accessible on all or nearly all sides cattle grazing on an ~ range  2.  a.  (1) being in a position or adjustment to permit passage ; not shut or locked an ~ door  (2) having a barrier (as a door) so adjusted as to allow passage the house was ~  b. having the lips parted stood there with his mouth wide ~  c. not buttoned or zipped an ~ shirt  3.  a. completely free from concealment ; exposed to general view or knowledge their hostilities eventually erupted with ~ war  b. exposed or vulnerable to attack or question ; subject ~ to doubt  c. being an operation or surgical procedure in which an incision is made such that the tissues are fully exposed  4.  a. not covered with a top, roof, or lid an ~ car her eyes were ~  b. having no protective covering ~ wiring an ~ wound  5. not restricted to a particular group or category of participants ~ to the public ~ housing: as  a. enterable by both amateur and professional contestants an ~ tournament  b. enterable by a registered voter regardless of political affiliation an ~ primary  6. fit to be traveled over ; presenting no obstacle to passage or view the ~ road ~ country  7. having the parts or surfaces laid out in an expanded position ; spread out ; unfolded an ~ book  8.  a.  (1) low 13  (2) formed with the tongue in a lower position Italian has an ~ and a close e  b.  (1) having clarity and resonance unimpaired by undue tension or constriction of the throat an ~ vocal tone  (2) of a tone produced by an ~ string or on a wind instrument by the lip without the use of slides, valves, or keys  9.  a. available to follow or make use of the only course ~ to us  b. not taken up with duties or engagements keep an hour ~ on Friday  c. not finally decided ; subject to further consideration the salary is ~ an ~ question  d. available for a qualified applicant ; vacant the job is still ~  e. remaining available for use or filling until canceled an ~ order for more items  f. available for future purchase these items are in ~ stock  g. available for breeding ; not now pregnant an ~ heifer  h. not proprietary ; available to third party developers ~ source code  10.  a. characterized by ready accessibility and usually generous attitude: as  (1) generous in giving  (2) willing to hear and consider or to accept and deal with ; responsive  (3) free from reserve or pretense ; frank  b. accessible to the influx of new factors (as foreign goods) an ~ market  11.  a. having ~ings, interruptions, or spaces ~ mesh: as  (1) being porous and friable ~ soil  (2) sparsely distributed ; scattered ~ population  (3) of a compound having components separated by a space in writing or printing (as opaque projector)  b. not made up of a continuous closed circuit of channels the insect circulatory system is ~  12.  a. of an organ pipe not stopped at the top  b. of a string on a musical instrument not stopped by the finger  13. being in operation an ~ microphone; especially ready for business, patronage, or use the store is ~ from 9 to 5 the new highway will be ~ next week  14.  a.  (1) characterized by lack of effective regulation of various commercial enterprises an ~ town  (2) not repressed by legal controls ~ gambling  b. free from checking or hampering restraints an ~ economy  c. relatively unguarded by opponents passed to an ~ teammate  15. having been ~ed by a first ante, bet, or bid the bidding is ~  16. of punctuation characterized by sparing use especially of the comma  17.  a. containing none of its endpoints an ~ interval  b. being a set or composed of sets each point of which has a neighborhood all of whose points are contained in the set THE INTERIOR OF A SPHERE IS AN ~ SET  18.  a. being an incomplete electrical circuit  b. not allowing the flow of electricity an ~ switch  19. of a universe having insufficient mass to halt expansion gravitationally  Synonyms: see frank, liable  • ~ adverb  • ~ly adverb  • ~ness noun  II. verb  (~ed; ~ing)  Date: before 12th century  transitive verb  1.  a. to move (as a door) from a closed position  b. to make available for entry or passage by turning back (as a barrier) or removing (as a cover or an obstruction)  2.  a. to make available for or active in a regular function ~ a new store  b. to make accessible for a particular purpose ~ed new land for settlement ~ the way for changes  c. to initiate access to (a computer file) prior to use  3.  a. to disclose or expose to view ; reveal  b. to make more discerning or responsive ; enlighten must ~ our minds to the problems  c. to bring into view or come in sight of by changing position  4.  a. to make an ~ing in ~ed the boil  b. to loosen and make less compact ~ the soil  5. to spread out ; unfold ~ed the book  6.  a. to enter upon ; begin ~ed the meeting  b. to commence action in a card game by making (a first bid), putting a first bet in (the pot), or playing (a card or suit) as first lead  7. to restore or recall (as an order) from a finally determined state to a state in which the parties are free to prosecute or oppose  intransitive verb  1. to become ~ the office ~ed early  2.  a. to spread out ; expand the wound ~ed under the strain  b. to become disclosed a beautiful vista ~ed before us  3. to become enlightened or responsive  4. to give access the rooms ~ onto a hall  5. speak out 2 finally he ~ed freely on the subject  6.  a. to begin a course or activity the play ~s on Tuesday  b. to make a bet, bid, or lead in commencing a round or hand of a card game  7. to provide the ~ing performance of a show before the main event  • ~ability noun  • ~able adjective  III. noun  Date: 13th century  1. ~ing  2. ~ and unobstructed space: as  a. ~ air  b. ~ water  3. an ~ contest, competition, or tournament  4. a public or unconcealed state or position