1. A hand tool used for opening sealed containers (bottles or cans)
   "He searched the drawer for a bottle opener to uncap the beverages"
    
2. A person who unfastens, unwraps or opens
   "He was the designated opener for all difficult jar lids";
   - undoer, unfastener, untier
    
3. The first event in a series
   "she played Chopin for her opener"; "the season's opener was a game against the Yankees"

1. Affording unobstructed entrance and exit; not shut or closed
   "they left the door open"; "an open door";
   - unfastened
    
2. Affording free passage or access
   "open ranks"; "open drains"; "the road is open to traffic"
    
3. Available to or viewable by the public
   "an open protest"; "an open letter to the editor"
    
4. With no protection or shield
   "open to the weather"; "an open wound";
   - exposed
    
5. Accessible to all
   "open season"; "an open economy"
    
6. Openly straightforward and direct without reserve or secretiveness
   "an open and trusting nature";
   - candid, heart-to-heart
    
7. Observable; not secret or hidden
   "open ballots";
   - overt
    
8. Used of mouth or eyes
   "keep your eyes open";
   - opened
    
9. Not brought to a conclusion; subject to further thought
   "an open question";
   - undecided, undetermined, unresolved
    
10. Not having been filled
    "the job is still open"
     
11. Not sealed or having been unsealed
    "the letter was already open";
    - opened
     
12. Without undue constriction as from e.g. tenseness or inhibition
    "the clarity and resonance of an open tone"; "her natural and open response"
     
13. Ready or willing to receive favourably
    "open to the proposals";
    - receptive
     
14. Not defended or capable of being defended
    "an open city"; "open to attack";
    - assailable, undefendable, undefended
     
15. (of textures) full of small openings or gaps
    "an open texture";
    - loose
     
16. Having no protecting cover or enclosure
    "open sports cars"; "an open boat"; "an open fire"
     
17. Not requiring union membership
    "an open shop employs nonunion workers"
     
18. Accepting, susceptible, or vulnerable to something specified
    "open to interpretation"; "an issue open to question";
    - capable, subject
     
19. Affording free passage or view
    "open waters"; "the open countryside";
    - clear
     
20. (set theory) of an interval that contains neither of its endpoints
    "The open interval (0, 1) includes all numbers greater than 0 and less than 1, but not 0 or 1 themselves"

Derived forms: openers

See also: acceptant, acceptive, admissive, agape, agaze, ajar, artless, assimilative, available, bald, barefaced, coarse, explicit, expressed, gaping, harsh, hospitable, ingenuous, naked, nonunion, opened, out on a limb, public, raw, staring, susceptible, unconcealed, unconstricted, undisguised, unenclosed, unobstructed, unprotected, unrestricted, unsealed, unsettled, unstoppered, visible, vulnerable, wide, wide-eyed, wide-open, yawning

Type of: actor, doer, hand tool, start, worker

Antonym: closed, covert, unopen [rare], unreceptive

Encyclopedia: Opener, Can, Hand, Folding, Type I