open

(Adjective) Physically unobstructed, uncovered, etc. Able to have something pass through or along it.
• Able to have something pass through or along it.
• Not covered, sealed, etc.; having an opening or aperture showing what is inside.
• Not physically drawn together, folded or contracted.
• Of a space, free of objects and obstructions.
• Resulting from an incision, puncture or any other process by which the skin no longer protects an internal part of the body.
• Unlocked or unlatched but not physically open.
• In a position allowing fluid to flow.
• Of a sandwich, etc.: composed of a single slice of bread with a topping.
• Not of a quality to prevent communication, as by closing waterways, blocking roads, etc.; hence, not frosty or inclement; mild; used of the weather or the climate.
• Able to be used or interacted with in some way. Available for use or operation.
• Available for use or operation.
• Actively conducting or prepared to conduct business.
• Allowing entrance to visitors or the public.
• Receptive.
• Susceptible or vulnerable (to the stated means).
• In current use; connected to as a resource.
• Running.
• Not hidden or restricted. Not concealed; overt.
• Not concealed; overt.
• Of a person, not concealing their feelings, opinions, etc.; candid, ingenuous.
• Public.
• Written or sent with the intention that it may made public or referred to at any trial, rather than by way of confidential private negotiation for a settlement.
• With open access, of open science, or both.
• Made public, usable with a free licence and without proprietary components.
• Of a tournament or competition, allowing anyone to enter, especially or originally irrespective of professional or amateur status.
• Characterised by free-flowing play.
• Not completed or finalised. Not settled; not decided or determined; not withdrawn from consideration.
• Not settled; not decided or determined; not withdrawn from consideration.
• Not fulfilled or resolved; incomplete.
• Not having one end joined to the other; not forming a closed loop.
• In a position such that a circuit is not completed, preventing electricity from flowing.
• Having different first and last vertices.
• Ending in a vowel; not having a coda.
• Having a free variable.
• Which is part of a predefined collection of subsets of X {\displaystyle X} , that defines a topological space on X {\displaystyle X} .
• Of a note, played without pressing the string against the fingerboard.
• Of a note, played without closing any finger-hole, key or valve.
• Uttered with a relatively wide opening of the articulating organs; said of vowels.
• Uttered, as a consonant, with the oral passage simply narrowed without closure.
• Source code of a computer program that is not within the text of a macro being generated.(Can we add an example for this sense?)
• Having component words separated by spaces, as opposed to being joined together or hyphenated; for example, time slot as opposed to timeslot or time-slot.
• Of a club, bat or other hitting implement, angled upwards and/or (for a right-hander) clockwise of straight.

(Verb) To make or become physically unobstructed, uncovered, etc. To make or become accessible or clear for passage by moving from a shut position.
• To make or become accessible or clear for passage by moving from a shut position.
• To make or become clear by removal of objects and obstructions, so as to allow passage, access, or visibility.
• To unseal or uncover, or become unsealed or uncovered.
• To spread; to expand into a wider or looser position.
• To make (a bed) ready for a patient by folding back the bedcovers.
• To reveal one's hand.
• To move to a position allowing fluid to flow.
• To angle (a club, bat or other hitting implement) upwards and/or (for a right-hander) clockwise of straight.
• To cause or allow a gap to form or widen.
• To move to a position preventing electricity from flowing.
• To make or become available for use or interaction. To make or become operative or available.
• To make or become operative or available.
• To make or become accessible to customers, clients or visitors.
• To make or become receptive or susceptible (to something).
• To connect to a resource (a file, document, etc.) for viewing or editing.
• To turn on; to switch on.
• To start or begin. To start (an event or activity) as the first performer or actor.
• To start (an event or activity) as the first performer or actor.
• To precede another as a performer at a concert or show.
• Of an event, activity etc., to start or get underway.
• To bring up, broach.
• To enter upon, begin.
• To start running (a program or application, especially one with a screen-based interface).
• To begin a side's innings as one of the first two batsmen.
• To bet before any other player has in a particular betting round in a game of poker.
• To make an open relationship or marriage, i.e., with possible additional relationships.
• To disclose; to reveal; to interpret; to explain.

(Noun) Open or unobstructed space; an exposed location.
• Public knowledge or scrutiny; full view.
• A defect in an electrical circuit preventing current from flowing.
• A sports event in which anybody can compete, especially or originally irrespective of amateur or professional status.
• The act of something being opened, such as an e-mail message.