mid-13c., "bad luck, misfortune, unlucky accident," from mis- (1) "bad" + hap (n.) "luck." It probably was formed on analogy of Old French mescheance (see mischance (n.)). Meaning "unfortunate event" is from mid-14c.

"mishap, ill-luck, disaster," c. 1300, from Old French mescheance "misfortune, mishap, accident; wickedness, malice," from Vulgar Latin *minuscadentiam; see mis- (2) + chance (n.). Now usually "bad luck;" formerly much stronger: "calamity, disaster, affliction."

"an unfortunate experience, a bad experience, ill-luck, calamity," c. 1300, misaventure, from Old French mesaventure (12c.) "accident, mishap," from mesavenir "to turn out badly;" see mis- (2) + adventure (n.) in the older sense of "that which happens by chance, fortune, luck." The spelling with -d- became regular after c. 1600.

mid-14c., "a return to health after illness, injury, misfortune, etc.," from Anglo-French recoverie (c. 1300), Old French recovree "remedy, cure, recovery," from past-participle stem of recovrer (see recover).

The meaning "a gaining possession (of property) by legal action" is from early 15c. The general (non-legal) sense of "act or power of regaining or retaking" (something lost or taken away) is by 1530s. That of "act of righting oneself after a blunder, mishap, etc." is from 1520s. The meaning "restoration from a bad to a good condition" is from 1580s.

mid-15c., "unfortunate event or circumstance," from mis- (1) "bad, wrong" + fortune. From c. 1500 as "adversity or ill fortune for which the sufferer is not directly responsible." In 19c., it was a euphemism for "illegitimate child." Related: Misfortunate.

Mischance is the lightest word for that which is really disagreeable; a mishap may be comparatively a trivial thing; both generally apply to the experience of individuals. Misfortune is the most general of these words; a misfortune is a really serious matter; it may befall a person, family, or nation. A very serious misfortune affecting large numbers is a calamity, the central idea of which is wide-spread and general mischief. [Century Dictionary, 1895]

"to happen ill, meet with misfortune, come to grief," mid-14c., from mis- (1) + happen. Related: Mishappened; mishappening. The word now is obsolete. Chaucer uses mishappy; mishappiness was in use 16c.-17c.

late 14c., "an occurrence, incident, event; what comes by chance," from Old French accident (12c.), from Latin accidentem (nominative accidens) "an occurrence; chance; misfortune," noun use of present participle of accidere "happen, fall out, fall upon," from ad "to" (see ad-) + combining form of cadere "to fall," from PIE root *kad- "to fall."

The sense has had a tendency since Latin to extend from "something that happens, an event" to "a mishap, an undesirable event." Latin si quid cui accidat, "if anything should happen to one," was a euphemism for "if one should die." In Middle English the word is met usually in theology (in reference to the material qualities in the sacramental bread and wine), medicine ("something out of the ordinary, disease, injury"), or philosophy ("non-essential characteristic of a thing").

From late 15c. as "the operations of chance." Meaning "an unplanned child" is attested by 1932. Accident-prone is from 1926.

early 13c., "what befalls one; state of affairs," from Old French cas "an event, happening, situation, quarrel, trial," from Latin casus "a chance, occasion, opportunity; accident, mishap," literally "a falling," from cas-, past-participle stem of cadere "to fall, sink, settle down, decline, perish" (used widely: of the setting of heavenly bodies, the fall of Troy, suicides), from PIE root *kad- "to fall."

The notion is of "that which falls" as "that which happens" (compare befall). From its general nature, the word has taken on widespread extended and transferred meanings. Meaning "instance, example" is from c. 1300. Meaning "actual state of affairs" is from c. 1400. In law, "an instance of litigation" (late 14c.); in medicine, "an instance of a disease" (late 14c.).

The grammatical sense, "one of the forms which make up the inflections of a noun" (late 14c.) also was in Latin, translating Greek ptōsis "declension," literally "a falling." "A noun in the nominative singular ..., or a verb in the present indicative ...,

is conceived as standing straight. Then it falls, or is bent, or

declines into various positions" [Gilbert Murray, "Greek Studies"]

U.S. slang meaning "person" (especially one peculiar or remarkable in any way) is from 1848. Meaning "incident or series of events requiring police investigation" is from 1838. In case "in the event" is recorded from mid-14c. Case-history is from 1879, originally medical; case-study "study of a particular case" is from 1879, originally legal; case-law "law as settled by previous court cases" is from 1861.