adjective

1. 1. in a state which permits access, entrance, or exit; not closed, covered, clogged, or shut open doors
   2. closed, but unlocked the car is open
2. 1. in a state which permits freedom of view or passage; not enclosed, fenced in, sheltered, screened, etc.; unobstructed; clear open fields
   2. having few or no trees, houses, etc. open country
3. unsealed; unwrapped
4. 1. not covered over; without covering, top, etc.
   2. vulnerable to attack, etc.; unprotected or undefended
5. spread out; unfolded; unclosed; expanded an open book
6. having spaces between; having gaps, holes, interstices, etc. open ranks
7. free from ice the lake is open
8. having relatively little snow or frost; mild an open winter
9. 1. that may be entered, used, competed in, shared, visited, etc. by all an open meeting
   2. ready to admitcustomers, clients, etc.
10. free to be argued or contested; not settled or decided an open question
11. 1. free from prejudice or bigotry; not closed to new ideas, etc. an open mind
    2. liberal; generous
12. 1. ☆ free from legal restrictions an open season on deer
    2. ☆ free from discriminatory restrictions based on race, religion, etc. open housing
    3. ☆ free from effective regulation with respect to drinking, gambling, etc. the city is wide open
    4. not regulated, organized, or conducted along traditional or conventional lines open marriage, open education
13. characterized by social mobility, political freedom, diversity of opinion, etc. an open society
14. in force or operation an open account
15. 1. not already taken, occupied, or engaged the job is still open
    2. free to be accepted or rejected
16. not closed against access; accessible; available
17. not hidden or secret; generally known; public an open quarrel
18. frank; candid; direct; honest an open manner
19. Math. of a set of points that is the complement of a closed set of points, as the set of all points outside a circle
20. Music
    1. not stopped by the finger: said of a string
    2. not closed at the top: said of an organ pipe
    3. produced by an open string or pipe, or, in wind instruments, brasses, etc., without a slide or key: said of a tone
    4. not muted
21. Phonet.
    1. articulated with the tongue as low as possible in the mouth; low: said of certain vowels
    2. articulated with the tongue in the lower of two possible positions the open e and close e in Italian
    3. articulated with the organs of speech not in close contact; fricative: said of certain consonants
    4. ending in a vowel or diphthong: said of a syllable
22. Printing
    1. designating or of a style of type the letters of which are cast in outline so that the inside of letters shows white
    2. with wide spacing between words or lines of type; not solid
23. Sports designating a stance, as of a golfer or batter in baseball, in which the front foot is farther than the rear foot from an imaginary straight line, as one joining tee and green or one joining home plate and second base

Etymology: ME < OE, akin to Ger offen < PGmc *upana: for IE base see up

transitive verb

1. to make or cause to be open; specif.,
   1. to unclose; unfasten open the door
   2. to remove obstructions from to open a drain
2. 1. to make an opening or openings in to open an abscess
   2. to make or produce (a hole, way, etc.)
3. to make spaces between; spread out; expand to open ranks
4. to unclose, unfold, or unroll to open a book
5. to make accessible or subject (to an influence or action); expose
6. to make available for use, competition, or participation, without restriction, taxation, fee, etc.
7. to free from prejudice and bigotry; make liberal and generous to open one's mind
8. to make known, public, etc.; reveal; disclose
9. to begin; enter upon; start; commence to open the bidding, a session, etc.
10. to cause to start operating, going, etc. to open a new shop
11. to undo, recall, or set aside (a judgment, settlement, etc.), so as to leave the matter open to further action

intransitive verb

1. to become open
2. to spread out; expand; unroll; unfold
3. to become free from prejudice, etc.; become liberal and generous
4. to become revealed, disclosed, etc.; come into view
5. to be or act as an opening; give access: with to, into, on, etc.
6. to begin; start
7. to start operating, going, bidding, etc.; specif., in the stock exchange, to show an indicated price level at the beginning of the day steel opened high
8. to begin a series of performances, games, etc.

noun