What Is Coincidence?

There are some define of 'Coincidence' from google.com:

an event that might have been arranged although it was really accidental
the quality of occupying the same position or area in space; "he waited for the coincidence of the target and the cross hairs"
concurrence: the temporal property of two things happening at the same time; "the interval determining the coincidence gate is adjustable"
wordnet.princeton.edu/perl/webwn

Coincidence is the noteworthy alignment of two or more events or circumstances without obvious causal connection. The word is derived from the Latin co- ("in," "with," "together") and incidere ("to fall on").
en.wikipedia.org/wiki/Coincidence

In Gann theory, a projected reversal point.
www.oryza.com/Reference-Library/Futures--Markets-Glossary/futures-market-terms.html

The ratio of the observed frequency of double crossings-over to the expected frequency, where the expected frequency is calculated by assuming that the two crossing-over events occur independently of each other.
www.fao.org/DOCREP/003/X3910E/X3910E06.htm

an apparently chance or unlikely event which creates an unexpected and significant situation, for example when the Cook in the Wilkie Collins story finds herself in the same house as the man who jilted her
www.longman.co.uk/tt_seceng/resources/glosauth.htm

the same value of the denoted intension in the actual world-time.
www.phil.muni.cz/~materna/rehabilitation_of_concepts.html

a novelist's...
www.enotes.com/marquez-masters/47153

Synonym for 'event': a note that two or more threads of interest are perceived to coincide in space, in time, or in some other way. Any meaning to be derived from the coincidence is independent of the coincidence itself; instead, it is dependent on context, and/or on the interpretive model used. ...
www.tomgraves.eu/tw_defn

The chance concurrence of two events having a peculiar correspondence between them.
www.calvertonschool.org/Waldspurger/pages/glossary_of_literary_terms.htm