Old English openung "act of making open" (a door, mouth, etc.), "disclosure, manifestation," verbal noun from present participle of open (v.). Meaning "vacant space, hole, aperture, doorway" is attested from c. 1200. Meaning "act of opening (a place, to the public)" is from late 14c.  Sense of "opportunity, chance" is from 1793. Sense of "action of beginning (something)" is from 1712; meaning "first performance of a play" is 1855; that of "start of an art exhibit" is from 1905. Opening night is attested from 1814.

Old English up, uppe, from Proto-Germanic *upp- "up" (source also of Old Frisian, Old Saxon up "up, upward," Old Norse upp; Danish, Dutch op; Old High German uf, German auf "up"; Gothic iup "up, upward," uf "on, upon, under;" Old High German oba, German ob "over, above, on, upon"), from PIE root *upo "under," also "up from under," hence also "over."

As a preposition, "to a higher place" from c. 1500; also "along, through" (1510s), "toward" (1590s). Often used elliptically for go up, come up, rise up, etc. Up the river "in jail" first recorded 1891, originally in reference to Sing Sing, which is up the Hudson from New York City. To drive someone up the wall (1951) is from the notion of the behavior of lunatics or caged animals. Insulting retort up yours (scil. ass) is attested by late 19c.

"anything that informs and enlightens," 1863, from eye (n.) + agent noun from open (v.). Earlier "alcoholic drink" especially one taken early in the day (1818).

short for open (adj.), early 13c. "not closed; not hidden;" originally as awake is from awaken, etc. As a verb, "to open," from mid-15c.; now obsolete or archaic. Middle English had ope-head "bare-headed" (c. 1300).

"outdoor, in the open air," 1520s, from open (adj.) + air (n.1).

"having no predetermined limit or boundary," 1825, from open (adj.) + end (n.).

"one who or that which opens," Old English openere, agent noun from open (v.). As "a tool or machine used in opening," c. 1600.

"liberal, generous," c. 1600, from open (adj.) + -handed. Related: Open-handedly; open-handedness.

"in an open manner, without secrecy," Old English openlice "manifestly, plainly, clearly, unreservedly;" see open (adj.) + -ly (2). It corresponds to Old Saxon opanlico, Old Frisian epplik, Dutch openlijk, Old High German offanliho, German öffentlich.

also openminded, "having an unreserved mind; frank, candid," also "having a mind accessible to new views, not narrow-minded, unprejudiced," 1828, first recorded in Carlyle; from open (adj.) + -minded. Figurative use of open (adj.) with reference to hearts, hands, etc. is from early 15c. Related: Open-mindedly; open-mindedness.

Could we hope that, in its present disjointed state, this emblematic sketch ["Wanderjahre"] would rise before the minds of our readers, in any measure as it stood before the mind of the writer; that, in considering it, they might seize only an outline of those many meanings which, at less or greater depth, lie hidden under it, we should anticipate their thanks for having, a first or a second time, brought it before them. As it is, believing that to open-minded, truth-seeking men, the deliberate words of an open-minded, truth-seeking man can in no case be wholly unintelligible, nor the words of such a man, as Goethe, indifferent, we have transcribed it for their perusal. [Carlyle, "Goethe," 1828]