Old English plante "young tree or shrub, herb newly planted, a shoot or strip recently sprouted from seed," from Latin planta "sprout, shoot, cutting" (source of Spanish planta, French plante), which is perhaps from an unattested verb *plantare "to drive in with the feet, push into the ground with the feet," or perhaps "to level the earth," from planta "sole of the foot," from nasalized form of PIE root *plat- "to spread." German Pflanz, Irish cland, Welsh plant also are from Latin.
Broader sense of "any small vegetable life, vegetation generally" (sometimes popularly excluding trees), "an individual living being with material organization but not animal in nature" is recorded by 1550s.
Most extended usages are from the verb, on the notion of "something planted;" such as "construction for an industrial process," 1789, at first with reference to the machinery, tools, apparatus, etc., later also the building; also slang meaning "a spy" (1812). Many of these follow similar developments in the French form of the word.
type of tall tree native to western Asia, southern Europe, and eastern U.S., also the large "nut" that it produces, 1560s, from chesten nut (1510s), with superfluous nut (n.) + Middle English chasteine, from Old French chastain (12c., Modern French châtaigne), from Latin castanea "chestnut, chestnut tree," from Greek kastaneia, which the Greeks explained as either "nut from Castanea" in Pontus, or "nut from Castana" in Thessaly, but probably both places are named for the trees, not the other way around, and the word is borrowed from a language of Asia Minor (compare Armenian kask "chestnut," kaskeni "chestnut tree"). In reference to the dark reddish-brown color, 1650s. Applied to the horse-chestnut by 1832.
The slang sense of "venerable joke or story" is from 1885, explained by U.S. actor Joseph Jefferson ("Lippincott's Monthly Magazine," January 1888) as probably abstracted from the 1816 melodrama "The Broken Sword" by William Dimond where an oft-repeated story involving a chestnut tree figures in an exchange between the characters "Captain Zavior" and "Pablo":
Zav. Let me see—aye! it is exactly six years since, that peace being restored to Spain, and my ship paid off, my kind brother offer'd me a snug hammock in the dwelling of my forefathers;—I mounted a mule at Barcelona, and trotted away for my native mountains. At the dawn of the fourth day's journey, I entered the wood of Collares, when, suddenly from the thick boughs of a cork-tree—
Pab. [Jumping up.] A chesnut, Captain, a chesnut!
Zav. Bah! you booby, I say, a cork.
Pab. And I swear, a chesnut—Captain! this is the twenty-seventh time I have heard you relate this story, and you invariably said, a chesnut, till now.
Zav. Did I? Well, a chesnut be it then. But, take your seat again.
Jefferson traced the connection through William Warren (1812-1888), "the veteran comedian of Boston" (and Jefferson's cousin) who often played Pablo in the melodrama.
Old English plantian "put or set in the ground to grow" (transitive and intransitive), also "introduce and establish, set up for the first time," from Latin *plantare "to plant, drive in with the feet" (see plant (n.)). Reinforced by cognate Old French planter.
Without reference to growing, "to insert firmly," late 14c. Of colonies, "introduce and establish new settlers in," from c. 1300. Figuratively, of ideas, etc., from early 15c. Meaning "to station (someone) for a surreptitious or secret purpose" is by 1690s; sense of "place (something) in a concealed place to mislead a later discoverer" is by 1865. In pugilistic slang, "to land, deliver" (a blow, etc.) by 1808. Meaning "to bury" is U.S. slang from U.S., 1855. Related: Planted; planting.
Old English wæter, from Proto-Germanic *watr- (source also of Old Saxon watar, Old Frisian wetir, Dutch water, Old High German wazzar, German Wasser, Old Norse vatn, Gothic wato "water"), from PIE *wod-or, suffixed form of root *wed- (1) "water; wet."
To keep (one's) head above water in the figurative sense is recorded from 1742. Water cooler is recorded from 1846; water polo from 1884; water torture from 1928. Linguists believe PIE had two root words for water: *ap- and *wed-. The first (preserved in Sanskrit apah as well as Punjab and julep) was "animate," referring to water as a living force; the latter referred to it as an inanimate substance. The same probably was true of fire (n.).
measure of quality of a diamond, c. 1600, from water (n.1), perhaps as a translation of Arabic ma' "water," which also is used in the sense "luster, splendor."
1590s, from horse (n.) + chestnut. A tree probably native to Asia, introduced in England c. 1550; the name also was extended to similar North American species such as the buckeye. Said to have been so called because it was food for horses, "but this is appar. a mere guess" [Century Dictionary] and the sense is perhaps "large," as in horseradish. The nut resembles that of the edible chestnut but is bitter to the taste.
1823, said to have been discovered on the coast of the Pacific northwest of North America during Cook's third expedition and so-named by the sailors, "from its striking resemblance to a large spider when it first appears above the surface, before the stem begins to rise from the spherical arrangement of the leaves, or the flagellae begin to creep to any distance from among them to the soil around" [Peter Sutherland, "Journal of a Voyage in Baffin's Bay," 1852]; from spider + plant (n.).