word-forming element of Latin origin meaning "half," also loosely, "part, partly; partial, almost; imperfect; twice," from Latin semi- "half" (before vowels often sem-, sometimes further reduced to se- before m-), from PIE *semi- "half" (source also of Sanskrit sami "half," Greek hēmi- "half," Old English sam-, Gothic sami- "half").

The Old English cognate, sam-, was used in such compounds as samhal "in poor health, weakly," literally "half-whole;" samsoden "half-cooked" ('half-sodden'), figuratively "stupid" (compare half-baked); samcucu "half-dead," etymologically "half-alive" (see quick (adj.)); and the lingering survivor, sandblind "dim-sighted" (q.v.).

The Latin element was common in formations from Late Latin, as in semi-gravis "half-drunk," semi-hora "half hour," semi-mortuus "half-dead," semi-nudus "half-naked," semi-vir "half-man, hermaphrodite."

The Latin-derived form in English has been active in forming native words since 15c. Semi-bousi "half-drunk" ('semi-boozy'), now obsolete, was among the earliest (c. 1400). As a noun, semi has variously been short for semi-detached house (by 1912), semi-trailer (by 1942), semi-final (by 1942).

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safety (n.)

early 14c., savete, "freedom or immunity from harm or danger; an unharmed or uninjured state or condition," from Old French sauvete, salvete "safety, safeguard; salvation; security, surety," earlier salvetet (11c., Modern French sauveté), from Medieval Latin salvitatem (nominative salvitas) "safety," from Latin salvus "uninjured, in good health, safe" (from PIE root *sol- "whole, well-kept"). From late 14c. as "means or instrument of safety, a safeguard."

The meaning "trigger-lock on a gun" is attested by 1881, perhaps short for safety-lock (1877), etc. As a North American football position, by 1931; as a type of score against one's own team, 1881.

Safety-valve, which diminishes the risk of explosion, is from 1797; figurative sense recorded from 1818. Safety-net in literal sense (in machinery) is by 1916, later of aerial circus performances (1920s); figurative use is by 1950. Safety-bicycle as a name for the modern type, with low, equal-sized wheels and a driving mechanism, is by 1866. Safety-razor is by 1877. A safety-belt (1840) was at first for window washers and firefighters; it was used of restraining straps for airplane pilots by 1911, extended to automobiles by 1948. Safety first as an accident-prevention slogan first recorded 1873.

Safety first, and saving of fuel second, should be the rule in steam engineering. [Scientific American, June 15, 1861]
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medicine (n.)

c. 1200, "medical treatment, cure, healing," also (early 14c.) "substance used in treatment of a disease, medicinal potion or plaster," also used figuratively of spiritual remedies, from Old French medecine (Modern French médicine) "medicine, art of healing, cure, treatment, potion" and directly from Latin medicina "the healing art, medicine; a remedy," also used figuratively.

This is perhaps originally ars medicina "the medical art," from fem. of medicinus (adj.) "of a doctor," from medicus "a physician" (from PIE root *med- "take appropriate measures"); though OED says evidence for this path is wanting and suggests derivation directly from medicus. The sense of "practice, theory, or study of curing, alleviating, or preventing disease in humans" is from mid-14c.

The figurative phrase take (one's) medicine "submit to something disagreeable" is recorded by 1865; that of dose of (one's) own medicine is by 1894. Medicine show "traveling show meant to attract a crowd so patent medicine can be sold to them" is American English, 1938. Medicine ball "stuffed leather ball used for exercise" is from 1889.

It is called a "medicine ball" and it got that title from Prof. [Robert J.] Roberts, now of Springfield, whose fame is widespread, and whose bright and peculiar dictionary of terms for his prescription department in physical culture is taught in every first-class conducted Y.M.C.A. gymnasium in America. Prof. Roberts calls it a "medicine ball" because playful exercise with it invigorates the body, promotes digestion, and restores and preserves one's health. [Scientific American Supplement, March 16, 1889]
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police (n.)
Origin and meaning of police

1530s, "the regulation and control of a community" (similar in sense to policy (n.1)); from Middle French police "organized government, civil administration" (late 15c.), from Latin politia "civil administration," from Greek polis "city" (see polis).

Until mid-19c. used in England for "civil administration;" application to "administration of public order, law-enforcement in a community" (1716) is from French (late 17c.), and originally in English referred to France or other foreign nations.

The sense of "an organized civil force for maintaining order, preventing and detecting crime, etc." is by 1800; the first force so-named in England was the Marine Police, set up 1798 to protect merchandise at the Port of London. Meaning "body of officers entrusted with the duty of enforcing laws, detecting crime, etc." is from 1810.

In its most common acceptation, the police signifies the administration of the municipal laws and regulations of a city or incorporated town or borough by a corps of administrative or executive officers, with the necessary magistrates for the immediate use of force in compelling obedience and punishing violation of the laws, as distinguished from judicial remedies by action, etc. The primary object of the police system is the prevention of crime and the pursuit of offenders; but it is also subservient to other purposes, such as the suppression of mendicancy, the preservation of order, the removal of obstructions and nuisances, and the enforcing of those local and general laws which relate to the public health, order, safety, and comfort. [Century Dictionary, 1895]

In constitutional law, police power is the power of a government to limit civil liberties and exercise restraint and compulsion over private rights, especially to advance or protect the public welfare. Police state "state regulated by means of national police" first recorded 1865, with reference to Austria. Police action in the international sense of "military intervention short of war, ostensibly to correct lawlessness" is from 1933. Police officer is attested from 1794, American English. Police station is from 1817. Police dog is by 1908.

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get (v.)

c. 1200, from Old Norse geta (past tense gatum, past participle getenn) "to obtain, reach; to be able to; to beget; to learn; to be pleased with," a word of very broad meaning, often used almost as an auxilliary verb, also frequently in phrases (such as geta rett "to guess right"). This is from Proto-Germanic *getan (source also of Old Swedish gissa "to guess," literally "to try to get"), from PIE root *ghend- "to seize, take."

Old English, as well as Dutch and Frisian, had the verb almost exclusively in compounds (such as begietan, "to beget;" forgietan "to forget"). Vestiges of an Old English cognate *gietan remain obliquely in modern past participle gotten and original past tense gat, also Biblical begat.

In compound phrases with have and had it is grammatically redundant, but often usefully indicates possession, obligation, or necessity, or gives emphasis. The word and phrases built on it take up 29 columns in the OED 2nd edition; Century Dictionary lists seven distinct senses for to get up.

"I GOT on Horseback within ten Minutes after I received your Letter. When I GOT to Canterbury I GOT a Chaise for Town. But I GOT wet through before I GOT to Canterbury, and I HAVE GOT such a Cold as I shall not be able to GET rid of in a Hurry. I GOT to the Treasury about Noon, but first of all I GOT shaved and drest. I soon GOT into the Secret of GETTING a Memorial before the Board, but I could not GET an Answer then, however I GOT Intelligence from the Messenger that I should most likely GET one the next Morning. As soon as I GOT back to my Inn, I GOT my Supper, and GOT to Bed, it was not long before I GOT to Sleep. When I GOT up in the Morning, I GOT my Breakfast, and then GOT myself drest, that I might GET out in Time to GET an Answer to my Memorial. As soon as I GOT it, I GOT into the Chaise, and GOT to Canterbury by three: and about Tea Time, I GOT Home. I HAVE GOT No thing particular for you, and so Adieu." [Philip Withers, "Aristarchus, or the Principles of Composition," London, 1789, illustrating the widespread use of the verb in Modern English]

As a command to "go, be off" by 1864, American English. Meaning "to seize mentally, grasp" is from 1892. Get wind of "become acquainted with" is from 1840, from earlier to get wind "to get out, become known" (1722). To get drunk is from 1660s; to get religion is from 1772; to get better "recover health" is from 1776. To get ready "prepare oneself" is from 1890; to get going "begin, start doing something" is by 1869 in American English; get busy "go into action, begin operation" is from 1904. Get lost as a command to go away is by 1947. To get ahead "make progress" is from 1807. To get to (someone) "vex, fret, obsess" is by 1961, American English (get alone as "to puzzle, trouble, annoy" is by 1867, American English). To get out of hand originally (1765) meant "to advance beyond the need for guidance;" sense of "to break free, run wild" is from 1892, from horsemanship. To get on (someone's) nerves is attested by 1970.

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