1957, "event that never happened;" 1958, "event that happened but fell so far short of expectations it might as well not have happened; unimportant or disappointing event;" from non- + event.

also counter-factual, "expressing a 'what if;' expressing what has not happened but could have," by 1946, from counter- + factual.

"before the atomic age," 1914, in "World Set Free," in which H.G. Wells anticipates the word the future would use to look back from a time defined by events that hadn't yet happened in his day; from pre- + atomic.

also tri-centennial, "comprising three hundred years; including or relating to an interval of three hundred years," 1818; as a noun, "day observed as a festival in commemoration of something that happened three hundred years before," 1872. See tri- + centennial.

Old English mihte, meahte, originally the past tense of may (Old English magen "to be able"), thus "*may-ed." The noun might-have-been "something that might have happened but did not," also "someone that might have been greater but wasn't," is by 1848.

1560s, "quality of being contingent, openness to chance or free will, the possibility that that which happens might not have happened," from contingent + abstract noun suffix -cy. Meaning "a chance occurrence, an accident, an event which may or may not occur" is from 1610s.

past tense and past participle of catch (v.), attested from 14c., predominant after c. 1800, replacing earlier catched. A rare instance of an English strong verb with a French origin. This might have been by influence of Middle English lacchen (see latch (v.)), which also then meant "to catch" and was more or less a synonym of catch (as their noun forms remain), and which then had past tense forms lahte, lauhte, laught. The influence would have happened before latch switched to its modern weak conjugation.