open
adj.adj. not closed or covered, so that people or things can go in or out. You use this to describe doors, windows, or businesses that are ready for customers.
adj. allowing access, passage, or view by not being closed or covered. Often follows a linking verb or sits before a noun.
The window is open and the room is cold.
The shop is open from nine to five every day except Sunday.
The architect designed the house with an open floor plan to ensure that natural light could reach every corner of the living space.
Adjective from Middle English open, from Old English open (“open”), from Proto-West Germanic opan, from Proto-Germanic upanaz (“open”), from Proto-Indo-European *upo (“up from under, over”). Cognates * Scots apen (“open”) * Saterland Frisian eepen (“open”) * West Frisian iepen (“open”) * Cimbrian offe (“open”) * Dutch open (“open”) * German offen (“open”) * Vilamovian ufa, uffa (“open”) * Yiddish אָפֿן (ofn, “open”) * Danish åben (“open”) * Icelandic opinn (“open”) * Norwegian Bokmål åpen (“open”) * Norwegian Nynorsk open (“open”) * Swedish öppen (“open”) Compare also Latin supinus (“on one's back, supine”), Albanian hap (“to open”). Related to up. Verb from Middle English openen, from Old English openian (“to open”), from Proto-West Germanic opanōn, from Proto-Germanic upanōną (“to raise; lift; open”), from Proto-Germanic *upanaz (“open”, adjective). Cognate with Saterland Frisian eepenje (“to open”), West Frisian iepenje (“to open”), Dutch openen (“to open”), German öffnen (“to open”), Danish åbne (“to open”), Swedish öppna (“to open”), Norwegian Bokmål åpne (“to open”), Norwegian Nynorsk and Icelandic opna (“to open”). Related to English up. Noun from Middle English open (“an aperture or opening”), from the verb. In the sports sense, however, a shortening of “open competition”.
Typically functions as a predicative adjective after 'be' or 'stay', or as an attributive adjective before a noun.
open the lightturn on the lightFor electrical devices like lights, TVs, or radios, the correct verb is 'turn on' or 'switch on', not 'open'.