Etymology
Advertisement
occur (v.)

1520s, "meet, meet in argument," from French occurrer "happen unexpectedly" or directly from Latin occurrere "run to meet, run against, befall, present itself," from ob "against, toward" (see ob-) + currere "to run" (from PIE root *kers- "to run"). Sense development is from "meet" to "present itself" to "appear" to "happen" ("present itself in the course of events"). Meaning "to come into one's mind" is from 1620s. Related: Occurred; occurring.

Related entries & more 
Advertisement
reoccur (v.)

also re-occur, "to occur again," 1803; see re- "back, again" + occur. Compare recur. Related: Reoccurred; reoccurring.

Related entries & more 
occurrence (n.)

"that which presents itself, that which happens without design or expectation," 1530s, from French occurrence "unexpected happening" or directly from Medieval Latin occurrentia, from Latin occurentem (nominative occurens), present participle of occurrere (see occur). The adjective occurrent "occurring, happening, incidental" (mid-15c.) is long obsolete.

Related entries & more 
*kers- 

Proto-Indo-European root meaning "to run."

It forms all or part of: car; career; cargo; caricature; cark; carpenter; carriage; carrier; carry; charabanc; charette; charge; chariot; concourse; concur; concurrent; corral; corridor; corsair; courant; courier; course; currency; current; curriculum; cursive; cursor; cursory; discharge; discourse; encharge; excursion; hussar; incur; intercourse; kraal; miscarry; occur; precursor; recourse; recur; succor.

It is the hypothetical source of/evidence for its existence is provided by: Greek -khouros "running;" Latin currere "to run, move quickly;" Lithuanian karšiu, karšti "go quickly;"Old Irish and Middle Welsh carr "cart, wagon," Breton karr "chariot," Welsh carrog "torrent;" Old Norse horskr "swift."

Related entries & more 
post-millennial (adj.)

also postmillennial, "relating to what may occur in the period following the millennium," 1831, from post- "after" + millennial; chiefly in reference to the Protestant doctrine that the second coming of Christ will occur after, not at, the Christian millennium. Related: Post-millennialism; post-millennialist.

Related entries & more 
Advertisement
happen (v.)
late 14c., happenen, "to come to pass, occur, come about, be the case," literally "occur by hap, have the (good or bad) fortune (to do, be, etc.);" extension (with verb-formative -n) of the more common hap (v.). Old English used gelimpan, gesceon, and Middle English also had befall. In Middle English fel it hap meant "it happened." Related: Happened; happening. Phrase happens to be as an assertive way to say "is" is from 1707.
Related entries & more 
cycle (v.)

1842, "revolve in cycles, occur or recur in cycles," from cycle (n.). Meaning "to ride a bicycle" is by 1881 (implied in cycling). Related: Cycled.

Related entries & more 
opioid (n.)

1957, from opium + -oid. Originally not clearly distinguished from opiate, but now generally "chemical product that works the same as an opiate but does not occur naturally."

Related entries & more 
unlikely (adj.)
late 14c., "not likely to occur," from un- (1) "not" + likely (adj.). Similar formation in Old Norse ulikligr, Middle Danish uligelig. Meaning "not likely to be true" is recorded from 1590s. Related: Unlikeliness; unlikelihood.
Related entries & more 
midlife (n.)

also mid-life, 1837, from mid (adj.) + life. Middle-life is from early 14c. Midlife crisis "transition of identity and self-confidence that can occur in middle-aged individuals" is attested by 1965 (crisis of mid-life is by 1963).

Related entries & more