1854, "a general accord or agreement of different parts in effecting a given purpose," originally a term in physiology; 1861, of persons "a general agreement in opinion;" from Latin consensus "agreement, accord," past participle of consentire "feel together," from assimilated form of com "with, together" (see con-) + sentire "to feel" (see sense (n.)). There is an isolated instance of the word from 1633.
1670s, "action of marking off of verse in metric feet," from Late Latin scansionem (nominative scansio) "a scanning," in classical Latin, "act of climbing," noun of action from past-participle stem of scandere "to climb" (see scan (v.)). There is a 1650s instance in English of the word in the literal sense of "action of climbing up."
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.
"execution by electricity," 1889, American English; noun of action from electrocute. Meaning "any death by electricity" is from 1897.
Electrocution, unless better performed than in the first instance, is a retrograde step rather than the contrary. The preliminary arrangements: the shaving of the head, the cutting of the clothing, the strapping in a chair, add much to the horror of the occasion. It is safe to say that electrocution is not the coming method of execution. [The Medical Era, vol. vii, no. 9, Sept. 1890]
c. 1600, "tendency, inclination, penchant" (a less severe sense now obsolete); 1640s as "state of being (self)-addicted" to a habit, pursuit, etc., from Latin addictionem (nominative addictio) "an awarding, a delivering up," noun of action from past-participle stem of addicere "to deliver, award; devote, consecrate, sacrifice" (see addict (v.)). In the sense "compulsion and need to take a drug as a result of prior use of it" from 1906, in reference to opium (there is an isolated instance from 1779 with reference to tobacco).