"hard aromatic seed of the fruit of a tree found in the East Indies," used as a spice on cookery, c. 1300, note-mug, from Old North French or Anglo-French *noiz mugue, from Old French nois muguete, an unexplained alteration of nois muscade "nut smelling like musk," from nois "nut" (from Latin nux, from PIE *kneu- "nut;" see nucleus) + Latin muscada, fem. of muscat "musky" (see muscat). Probably influenced in English by Medieval Latin nux maga (compare unaltered Dutch muskaatnoot, German muscatnuß, Swedish muskotnöt).

American English colloquial wooden nutmeg "anything false or fraudulent" is from 1827; Connecticut is called the Nutmeg State "in allusion to the story that wooden nutmegs are there manufactured for exportation." [John Russell Bartlett, "Dictionary of Americanisms," 1859]

At a dinner party, the other day, during a little playful discussion of Yankee character, a bland and benevolent-looking old gentleman at my side informed me that he had come to the conclusion that the wooden-nutmeg story was neither more nor less than a mischievous satire. "For," said he, "there would be such an amount of minute carving required to make a successful imitation of the nutmeg, that the deception would hardly pay the workman. For myself, I do not believe the cheat was ever practised." I thanked him in the name of my country for the justice done her, and assured him that the story of the Yankee having whittled a large lot of unsaleable shoe-pegs into melon seeds, and sold them to the Canadians, was also a base fabrication of our enemies. [Grace Greenwood, "Haps and Mishaps of a Tour in Europe in 1853"]

c. 1600, from Irish lupracan, metathesis of Old Irish luchorpan, which traditionally is explained as literally "a very small body," from lu "little, small" (from PIE root *legwh- "not heavy, having little weight") + corpan, diminutive of corp "body," from Latin corpus "body" (from PIE root *kwrep- "body, form, appearance"). However, Celtic linguistic scholarship has recently found a different explanation and connected the word to Latin Lupercalia:

New research by Simon Rodway, Michael Clarke and Jacopo Bisagni, published in the journal Cambrian Medieval Celtic Studies, traces them back to the Roman Luperci. The Luperci were bands of aristocratic youths who ran naked through ancient Rome in the festival of Lupercalia on the 15 February. In the fifth century A.D. St Augustine of Hippo compared the Luperci with the Greek werewolves who were believed to change from men into wolves by swimming through a lake in Arcadia. Two centuries later Irish scholars misunderstood Augustine. They thought he meant that the Luperci were an ancient non-human race. Because they could swim they were supposed to have survived Noah's Flood and taken refuge in Ireland. So in medieval Irish legends the leprechauns or 'little Luperci' still lived under water. The wolf connection was soon forgotten and eventually the 'little Lupercus' became the familiar land-dwelling leprechaun of modern Irish folklore and tourism. [Patrick Sims-Williams, Professor of Celtic Studies in Aberystwyth University, Wales, cited at Languagelog]

Commonly spelled lubrican in 17c. English; "Century Dictionary" (1902) has it under leprechawn. Variant leithbragan probably is Irish folk etymology, from leith "half" + brog "brogue," because the spirit was "supposed to be always employed in making or mending a single shoe."

Old English softe, earlier sefte, "gentle, mild-natured; easeful, comfortable, calm, undisturbed; luxurious," from West Germanic *samfti, from Proto-Germanic *samftijaz "level, even, smooth, gentle, soft" (source also of Old Saxon safti, Old High German semfti, German sanft; and from a variant form with -ch- for -f-, Middle Dutch sachte, Dutch zacht, German sacht), from PIE root *sem- (1) "one; as one, together with" (the source of seem andsame). The etymological sense would be "smooth and agreeable," to the touch, senses, or mind.

From c. 1200 of persons, hearts, etc., "tender, yielding to emotions," also "easily moved or swayed; soft-hearted, sympathetic; docile." It is attested from late 14c. as "indulgent," also "physically feeble; effeminate, easily overcome, lacking manly courage." The meaning "foolish, simple, silly" is attested from 1620s.

It is attested from mid-13c. of material things, "not stiff, not coarse, fine; yielding readily to pressure." Of sounds or voices, "quiet, not loud or harsh," from early 13c. Of words, "mild, restrained; courteous" mid-14c. From late 14c. of wind, rain, etc.

From 1755 of water ("relatively free from mineral salts"), from 1789 of coal (generally meaning bituminous as opposed to anthractic). In reference to drinks, "non-alcoholic" by 1880. Of letters (-c-, -g-, etc.) when pronounced with more sibilance and less plosiveness, 1630s.

In reference to technology, "using natural resources," by 1974, perhaps 1970. Of a science or methods or data, "not subject to experimental verification, not mathematical," c. 1960.

Many phrases simply are contrasts to earlier ones in hard: Soft landing is from 1958 and the U.S. space program; soft rock as a music style is attested from 1969. Soft spot "weak or vulnerable place," literal and figurative, is by 1933, colloquial. The soft sell sales pitch that relies on gentle persuasions is so called by 1955. Soft-shoe as a dancing style is attested from 1927. The photographic soft-focus (adj.), in reference to camera lenses or shots, is from 1917; figurative use of it is by 1961. The softer sex "women collectively" is from 1640s.

1907 (from 1903 as a French word in English), "malicious damaging or destruction of an employer's property by workmen," from French sabotage, from saboter "to sabotage, bungle," literally "walk noisily," from sabot "wooden shoe" (see sabaton).

In English, "malicious mischief" would appear to be the nearest explicit definition of "sabotage," which is so much more expressive as to be likely of adoption into all languages spoken by nations suffering from this new force in industry and morals. Sabotage has a flavor which is unmistakable even to persons knowing little slang and no French .... [Century Magazine, November 1910] 

In French, and at first in English, the sense of "deliberately and maliciously destroying property" was in reference to labor disputes, but the oft-repeated story (as old as the record of the word in English) that the modern meaning derives from strikers' supposed tactic of throwing shoes into machinery is not supported by the etymology. Likely it was not meant as a literal image; the word was used in French in a variety of "bungling" senses, such as "to play a piece of music badly."

This, too, was the explanation given in some early usages:

SABOTAGE [chapter heading] The title we have prefixed seems to mean "scamping work." It is a device which, we are told, has been adopted by certain French workpeople as a substitute for striking. The workman, in other words, purposes to remain on and to do his work badly, so as to annoy his employer's customers and cause loss to his employer. [The Liberty Review, January 1907]

You may believe that sabotage is murder, and so forth, but it is not so at all. Sabotage means giving back to the bosses what they give to us. Sabotage consists in going slow with the process of production when the bosses go slow with the same process in regard to wages. [Arturo M. Giovannitti, quoted in report of the Sagamore Sociological Conference, June 1907]

The military extension to damage inflicted (especially clandestinely) to disrupt an enemy is from World War I.