early 15c., invencioun, "finding or discovering of something," from Old French invencion (13c.) and directly from Latin inventionem (nominative inventio) "faculty of invention," noun of action from past-participle stem of invenire "to come upon, find; find out; invent, discover, devise; ascertain; acquire, get, earn," from in- "in, on" (from PIE root *en "in") + venire "to come" (from a suffixed form of PIE root *gwa- "to go, come").

The sense of "thing invented" is first recorded 1510s; that of "act or process of finding out how to make or do" is from 1530s.

Invention is applied to the contrivance and production of something, often mechanical, that did not before exist, for the utilization of powers of nature long known or lately discovered by investigation. Discovery brings to light what existed before, but was not known. [Century Dictionary]

The earliest sense of the word in Middle English was "devised method of organization" (c. 1400), a sense now obsolete. The meaning "finding or discovery of something" is preserved in Invention of the Cross, Church festival (May 3) celebrating the reputed finding of the Cross of the Crucifixion by Helena, mother of Constantine, in 326 C.E. The related classical Latin word for "a device, contrivance" was inventum.

late 13c., "musical instrument, mechanical apparatus for producing musical sounds," from Old French instrument, enstrument "means, device; musical instrument" (14c., earlier estrument, 13c.) and directly from Latin instrumentum "a tool, an implement; means, furtherance; apparatus, furniture; ornament, dress, embellishment; a commission, authorization; a document," from instruere "arrange, prepare, set in order; inform, teach," literally "to build, erect," from in- "on" (from PIE root *en "in") + struere "to pile, build" (from PIE *streu-, extended form of root *stere- "to spread").

The word in other Germanic languages also is from French. In English the meaning "a means, an agency" is from mid-14c. The sense of "hand-tool, implement, utensil, something used to produce a mechanical effect" is from early 14c. "Now usually distinguished from a tool, as being used for more delicate work or for artistic or scientific purposes" [OED]. The legal meaning "written document by which formal expression is given to a legal act" is from early 15c. Formerly also used of body parts or organs with special functions.

In wyfhode I wol vse myn Instrument As frely as my makere hath it sent. [Chaucer, "Wife of Bath's Prologue"]

A book containing either all or the principal words of a language, or words of one or more specified classes, arranged in a stated order, usually alphabetical, with definitions or explanations of their meanings and other information concerning them, expressed either in the same or in another language; a word-book; a lexicon; a vocabulary .... [Century Dictionary]

1520s, from Medieval Latin dictionarium "collection of words and phrases," probably a shortening of dictionarius (liber) "(book) of words," from Latin dictionarius "of words," from dictio "a saying, expression," in Late Latin "a word," noun of action from past-participle stem of dicere "speak, tell, say," from PIE root *deik- "to show," also "pronounce solemnly."

The Medieval Latin word is said to have been first used by Johannes de Garlandia (John of Garland) as the title of a Latin vocabulary published c. 1220. Probably first English use in title of a book was in Sir Thomas Elyot's "Latin Dictionary" (1538).

As an adjective, "of or pertaining to a dictionary," from 1630s.  Dictionarist "compiler of a dictionary" (1610s) is older than dictionarian (1806 as a noun, 1785 as an adjective). Grose's 1788 "Dictionary of the Vulgar Tongue" has "RICHARD SNARY. A dictionary."

DICTIONARY, n. A malevolent literary device for cramping the growth of a language and making it hard and inelastic. This dictionary, however, is a most useful work. [Bierce]

late 13c., "covering of woven cloth or leather for the lower part of the leg, with or without feet," from late Old English hosa "covering for the leg," from Proto-Germanic *huson- (source also of Old Saxon, Old Norse hosa "covering for the leg between the knee and ankle," Middle High German hose "covering for the leg," German Hose "trousers," Danish hose "hose, stockings;" Middle Dutch hose, Dutch hoos "hose, stocking," also "spout, waterspout"), literally "covering," from PIE root *(s)keu- "to cover, conceal." Old French hose, Old Spanish huesa, Italian uosa are of Germanic origin.

From mid-15c. as "close-fitting garment resembling tights worn by men and boys."

The hose of the middle ages generally covered the person from the waist to the toes; they were secured to the upper garment by points or some similar device. At times the covering of one leg and side of the body was of different material and color from that of the other side. In the sixteenth century the leg-coverings were divided into two parts, and the word hose was applied rather to the breeches, the covering of the lower part of the leg and foot being called the stocking or nether-stock. [Century Dictionary]

Used in Middle English of various things resembling a stocking, such as the sheath or husk of an ear of grain; sense of "flexible rubber tube for conveying liquid" is first attested mid-14c.

"means of fastening," Old English loc "bolt, appliance for fastening a door, lid, etc.; barrier, enclosure; bargain, agreement, settlement, conclusion," from Proto-Germanic *lukana-, a verbal root meaning "to close" (source also of Old Frisian lok "enclosure, prison, concealed place," Old Norse lok "fastening, lock," Gothic usluks "opening," Old High German loh "dungeon," German Loch "opening, hole," Dutch luik "shutter, trapdoor").

Ordinary mechanical locks work by means of an internal bolt or bar which slides and catches in an opening made to receive it. "The great diversity of meaning in the Teut. words seems to indicate two or more independent but formally identical substantival formations from the root" [OED]. The Old English sense "barrier, enclosure" led to the specific meaning "barrier on a stream or canal" (c. 1300), and the more specific sense "gate and sluice system on a water channel used as a means of raising and lowering boats" (1570s).

From 1540s as "a fastening together," hence "a grappling in wrestling" (c. 1600). In firearms, the part of the mechanism which explodes the charge (1540s, probably so called for its resemblance to a door-latching device), hence figurative phrase lock, stock, and barrel (which add up to the whole firearm) "the whole of something" (1842). Phrase under lock and key attested from early 14c.

1794, the name of a fire-protection device to be used in theaters, a literal iron curtain; see iron (n.) + curtain (n.).

The new and exquisitely beautiful theatre of Drury-lane has the peculiar contrivance of an iron-curtain to secure the audience from all danger, in case of fire on the stage. Miss Farren, in the occasional epilogue, delivered on opening this new theatre, pleasantly informs the spectators that, should flames burst out in the part appropriated to the representation, they may comfort themselves with thinking that nothing can be burnt but the scenery and the actors. [The Monthly Review, June 1794]

From 1819 in the figurative sense "impenetrable barrier." In reference to the Soviet occupation of Eastern Europe, famously coined by Winston Churchill March 5, 1946, in speech at Westminster College, Fulton, Missouri, but it had been used earlier in this context (for example by U.S. bureaucrat Allen W. Dulles at a meeting of the Council on Foreign Relations, Dec. 3, 1945). The phrase had been used in the sense of "barrier at the edge of the sphere of influence of the Soviet Union" from 1920. During World War II, Goebbels used it in German (ein eiserner Vorhang) in the same sense. But its popular use in the U.S. dates from Churchill's speech.

"next in order after the fourth; an ordinal numeral; being one of five equal parts into which a whole is regarded as divided;" c. 1200, fift, from Old English fifta "fifth," from Proto-Germanic *finftan- (source also of Old Frisian fifta, Old Saxon fifto, Old Norse fimmti, Dutch vijfde, Old High German fimfto, German fünfte, Gothic fimfta),from *fimfe "five" (from PIE root *penkwe- "five") + *-tha, the word-forming element used to make ordinal numbers (see -th (1)). Normal development would have yielded fift; altered 14c. by influence of fourth.

Noun meaning "fifth part of a gallon of liquor" is first recorded 1938, American English; the noun in the music sense is from 1590s. Fifth Avenue (in New York City) has been used figuratively for "elegance, taste" at least since 1858. Fifth wheel "superfluous person or thing" attested from 1630s. It also was the name of a useful device, "wheel-plate or circle iron of a carriage" placed on the forward axle for support and to facilitate turning (1825). And the phrase sometimes is turned on its head and given a positive sense of "that which a prudent driver ought to take with him in case one of the others should break" (1817). Fifth-monarchy-man, 17c. for "anarchist zealot," is a reference to Daniel ii.44.

1580s, "damage to one's reputation," from French scandale, from Late Latin scandalum "cause for offense, stumbling block, temptation," from Greek skandalon "a stumbling block, offense; a trap or snare laid for an enemy."

The Greek noun in this form seems to be attested first in Septuagint (25 times) and the Greek New Testament (15 times) as "cause of moral stumblings," translating a Hebrew word meaning "a noose, a snare." The Biblical use is presumably figurative or metaphoric, and OED and others conclude that it is "certainly an old word meaning 'trap' " or a variant of one. Presumably, then, originally "trap with a springing device" (compare related skandalē "stick of a trap," the trigger which is pulled by the cord to spring it), if it is from PIE *skand- "to leap, climb" (see scan (v.), as is proposed in Watkins (Beekes is skeptical); also see slander (n.), which is another form of the same word.

The word is used in "Ancrene Riwle" (c. 1200), scandle, "discredit to religion resulting from bad behavior by a religious person," from Old French escandle, eschandle (12c.); Anglo-French scandle, and Latin scandalum. But the modern word likely is a new borrowing.

The meanings "malicious gossip" and "shameful condition, action, or event; that which causes scandal" are from 1590s; the sense of "person whose conduct is a disgrace" is by 1630s. Scandal sheet "sensational newspaper" is by 1884. Scandal-monger is from 1702.

mid-14c., in classical mythology, "sea nymph who by her singing lures sailors to their destruction," from Old French sereine (12c., Modern French sirène) and directly from Latin Siren (Late Latin Sirena), from Greek Seiren ["Odyssey," xii.39 ff.], one of the Seirēnes, the mythical sisters who enticed sailors to their deaths with their songs, also in Greek "a deceitful woman," perhaps literally "binder, entangler," from seira "cord, rope."

The meaning "mechanical device that makes a warning sound" is recorded by 1879, in reference to steamboats, perhaps from similar use of the French word. It later was extended to such devices for air raids, factory shifts, police cars, etc. In 20c. this use was sometimes spelled sireen.

The figurative sense of "one who sings sweetly and charms and allures" is recorded from 1580s. The classical descriptions of them were mangled in medieval translations and glosses, resulting in odd notions of their appearance. In English they generally were portrayed as harpies, but "In early use frequently confused with the mermaid" [OED]. Also in Middle English the name of a imaginary species of flying serpents, based on glossary explanations of Latin sirenes in Vulgate (Isaiah xiii.22).

For adjectives the Elizabethans tried sirenean, sirenian, sirenic, sirenical, sireny. Ruskin used sirenic, so it might be called the survivor.

late 13c., "recollection (of someone or something); remembrance, awareness or consciousness (of someone or something)," also "fame, renown, reputation;" from Anglo-French memorie (Old French memoire, 11c., "mind, memory, remembrance; memorial, record") and directly from Latin memoria "memory, remembrance, faculty of remembering," abstract noun from memor "mindful, remembering," from PIE root *(s)mer- (1) "to remember."

Sense of "commemoration" (of someone or something) is from c. 1300. Meaning "faculty of remembering; the mental capacity of retaining unconscious traces of conscious impressions or states, and of recalling these to consciousness in relation to the past," is late 14c. in English. Meaning "length of time included in the consciousness or observation of an individual" is from 1520s. 

I am grown old and my memory is not as active as it used to be. When I was younger I could remember anything, whether it had happened or not; but my faculties are decaying now and soon I shall be so I cannot remember any but the things that never happened. It is sad to go to pieces like this, but we all have to do it. ["Mark Twain," "Autobiography"]

Meaning "that which is remembered; anything fixed in or recalled to the mind" is by 1817, though the correctness of this use was disputed in 19c. The word was extended, with more or less of figurativeness, in 19c. to analogous physical processes. Computer sense, "device which stores information," is from 1946. Related: Memories.