Online Etymology Dictionary

mare (2): "broad, dark areas of the moon," 1765, from L. mare "sea" (see marine), applied to lunar features by Galileo and used in 17c. Latin works. They originally were thought to be actual seas.
mare (1): "female horse," O.E. mere (Mercian), myre (W.Saxon), fem. of O.E. mearh "horse," from P.Gmc. *markhjon (cf. O.S. meriha, O.N. merr, O.Fris. merrie, Ger. Mähre "mare"), said to be of Gaulish origin (cf. Ir. and Gael. marc, Welsh march, Bret. marh "horse"). No known cognates beyond Gmc. and Celtic. As the name of a throw in wrestling, it is attested from c.1600. Mare's nest "illusory discovery, excitement over something which does not exist" is from 1610s.
jade (2): "worn-out horse," late 14c., possibly from O.N. jalda "mare," from Finno-Ugric (cf. Mordvin al'd'a "mare"). As a term of abuse for a woman, it dates from 1560.
nightmare: late 13c., "an evil female spirit afflicting sleepers with a feeling of suffocation," compounded from night + mare "goblin that causes nightmares, incubus," from O.E. mare "incubus," from mera, mære, from P.Gmc. *maron "goblin," from PIE *mora- "incubus," from base *mer- "to rub away, harm, seize" (cf. first element in O.Ir. Morrigain "demoness of the corpses," lit. "queen of the nightmare," also Bulg., Serb., Pol. mora "incubus;" Fr. cauchemar, with first element is from O.Fr. caucher "to trample"). Meaning shifted mid-16c. from the incubus to the suffocating sensation it causes. Sense of "any bad dream" first recorded 1829; that of "very distressing experience" is from 1831.
Armorica: late 14c., ancient name for Brittany, from Gallo-Romance Are-mor-ica, lit. "before the sea," with a Celtic prefix meaning "before" (cf. O.Ir. ar) + mare "sea."
maritime: 1550, from M.Fr. maritime, from L. maritimus "of the sea," from mare (gen. maris) "sea" + L. ending -timus, originally a superl. suffix (cf. intimus "inmost," ultimus "last"), here denoting "close association with."
shank: O.E. sceanca "leg, shank, shinbone," from P.Gmc. *skankon- (cf. M.L.G. schenke, Ger. schenkel "shank, leg"), perhaps lit. "that which bends," from PIE base *skeng- "crooked" (cf. O.N. skakkr "wry, distorted," Gk. skazein "to limp"). Specifically, the part of the leg from the knee to the ankle. Shank's mare "one's own legs as a means of transportation" is attested from 1774. The verb, originally in golf, meaning "to strike (the ball) with the heel of the club" is recorded from 1927.
Mediterranean: c.1400, from L.L. Mediterraneum mare "Mediterranean Sea" (7c.), from L. mediterraneus "midland;" original sense being of "sea in the middle of the earth," from medius "middle" (see medial) + terra "land, earth" (see terrain). The O.E. name was Wendel-sæ, so called for the Vandals, Gmc. tribe that settled on the southwest coast of it after the fall of Rome.
Dead Sea: mid-13c., from dead + sea; its water is 26 percent salt (as opposed to 3 or 4 percent in most oceans) and supports practically no life. In the Bible it was the "Salt Sea" (Heb. yam hammelah), also "Sea of the Plain" and "East Sea." In Arabic it is al-bahr al-mayyit "Dead Sea." The ancient Greeks knew it as he Thalassa asphaltites "the Asphaltite Sea." Latin Mare Mortum, Gk. he nekra thalassa (both "The Dead Sea") referred to the sea at the northern boundaries of Europe, the Arctic Ocean.
marine (adj.): early 15c., from M.Fr. marin (fem. marine), from O.Fr. marin, from L. marinus (fem. marina) "of the sea," from mare (gen. maris) "sea," from PIE *mori-/*mari- "body of water, lake." Cognate with O.E. mere "sea, lake, pool, pond," from P.Gmc. *mari. Noun meaning "soldier who serves on a ship" is from 1670s, from Fr. marine, from the O.Fr. adjective.
ocean: late 13c., from O.Fr. occean (12c.), from L. oceanus, from Gk. okeanos, the great river or sea surrounding the disk of the Earth (as opposed to the Mediterranean), of unknown origin. Personified as Oceanus, son of Uranus and Gaia and husband of Tethys. In early times, when the only known land masses were Eurasia and Africa, the ocean was an endless river that flowed around them. Until c.1650, commonly ocean sea, translating L. mare oceanum. Application to individual bodies of water began 14c.; there are usually reckoned to be five of them, but this is arbitrary; also occasionally applied to smaller subdivisions, e.g. German Ocean "North Sea."
marshal: early 13c., from O.Fr. mareschal, originally "stable officer, horse tender, groom" (Frankish L. mariscaluis) from Frank. *marhskalk, lit. "horse-servant" (cf. O.H.G. marahscalc "groom"), from P.Gmc. *markhaz "horse" (see mare (1)) + *skalkaz "servant" (cf. Du. schalk "rogue, wag," Goth. skalks "servant"). Cognate with O.E. horsþegn. For development history, cf. constable. The verb "to arrange for fighting" is from 1580s. Related: Marshaled.
stud (2): "horse used for breeding," O.E. stod "herd of horses, place where horses are kept for breeding," from P.Gmc. *stodo (cf. O.N. stoð, M.L.G. stod, O.H.G. stuot "herd of horses," Ger. Stute "mare"), from PIE base *sta- "to stand" (cf. O.C.S. stado "herd," Lith. stodas "a drove of horses;" see stet). Sense of "male horse kept for breeding" is first recorded 1803; meaning "man who is highly active and proficient sexually" is attested from 1895; that of "any young man" is from 1929.
henchman: 1360, hengestman "high-ranking servant," originally "groom," from man + O.E. hengest "horse, stallion, gelding," from P.Gmc. *khangistas (cf. O.Fris. hengst, Du. hengest, Ger. Hengst "stallion"), probably lit. "best at springing," from PIE *kenku- (cf. Gk. kekiein "to gush forth;" Lith. sokti "to jump, dance;" Breton kazek "a mare," lit. "that which belongs to a stallion"). Became obsolete, but retained in Scottish as "personal attendant of a Highland chief," in which sense Scott revived it in literary Eng. in 1810. Sense of "obedient or unscrupulous follower" is first recorded 1839, probably based on a misunderstanding of the word as used by Scott.
mere (n.): O.E. mere "sea, lake, pool, pond," from P.Gmc. *mari (cf. O.N. marr, O.S. meri "sea," Du. meer "lake," O.H.G. mari, Ger. Meer "sea," Goth. marei "sea," mari-saiws "lake"), from PIE *mori-/*mari "sea" (cf. L. mare, O.C.S. morje, Rus. more, Lith. mares, O.Ir. muir, Welsh mor "sea," Gaulish Are-morici "people living near the sea").
mule (1): "offspring of donkey and horse," O.E. mul, O.Fr. mul (fem. mule), both from L. mulus (fem. mula) "a mule," probably from a pre-Latin Mediterranean language.
"The mule combines the strength of the horse with the endurance and surefootedness of the ass, and is extensively bred for certain employments for which it is more suited than either; it is ordinarily incapable of procreation. With no good grounds, the mule is a proverbial type of obstinacy." [OED]
Properly, the offspring of a he-ass and a mare; that of a she-ass and a stallion is technically a hinny. Used allusively of hybrids and things of mixed nature. As a type of spinning machine, attested from 1797. Meaning "stubborn person" is from 1848; that of "narcotics smuggler or courier" first attested 1935. O.Fr. mul was replaced in Fr. by dim. form mulet, hence muleteer "mule driver" (1538), from Fr. muletier.
sea: O.E. sæ "sheet of water, sea, lake," from P.Gmc. *saiwaz (cf. O.S. seo, O.Fris. se, M.Du. see), of unknown origin, outside connections "wholly doubtful" (Buck). Gmc. languages also use the general IE word (represented by Eng. mere), but have no firm distinction between "sea" and "lake," either by size or by salt vs. fresh. This may reflect the Baltic geography where the languages are thought to have originated. The two words are used more or less interchangeably, and exist in opposite senses (e.g. Goth. saiws "lake," marei "sea;" but Du. zee "sea," meer "lake"). Cf. also O.N. sær "sea," but Dan. sø, usually "lake" but "sea" in phrases. Ger. See is "sea" (fem.) or "lake" (masc.). Meaning "dark area of the moon's surface" is attested from 1667 (see mare (2)). Phrase sea change "transformation" is attested from 1610, first in Shakespeare ("The Tempest," I.ii). Sea legs is from 1712; sea serpent attested from 1646; sea level first recorded 1806. At sea in the fig. sense of "perplexed" is attested from 1768, from lit. sense of "out of sight of land."
ride: O.E. ridan "ride" (as on horseback), "move forward, rock" (class I strong verb; past tense rad, pp. riden), from P.Gmc. *ridanan (cf. O.N. riða, O.Fris. rida, M.Du. riden, Ger. reiten), from PIE *reidh- "to ride" (cf. O.Ir. riadaim "I travel," O.Gaul. reda "chariot"). Meaning "heckle" is from 1912; that of "have sex with (a woman)" is from 1250; that of "dominate cruelly" is from 1583. The noun is first recorded 1759; slang meaning "a motor vehicle" is recorded from 1930; sense of "amusement park device" is from 1934. To ride out "endure (a storm, etc.) without great damage" is from 1529. To ride shotgun is 1963, from Old West stagecoach custom in the movies. To ride shank's mare "walk" is from 1846. To take (someone) for a ride "tease, mislead, cheat," is first attested 1925, Amer.Eng., possibly from underworld sense of "take on a car trip with intent to kill" (1927). Phrase go along for the ride "join in passively" is from 1960. A ride cymbal (1956) is used by jazz drummers for keeping up continuous rhythm, as opposed to a crash cymbal (ride as "rhythm" in jazz slang is recorded from 1936).
Whig: British political party, 1657, in part perhaps a disparaging use of whigg "a country bumpkin" (c.1645); but mainly a shortened form of Whiggamore (1649) "one of the adherents of the Presbyterian cause in western Scotland who marched on Edinburgh in 1648 to oppose Charles I." Perhaps originally "a horse drover," from dialectal verb whig "to urge forward" + mare. The name was first used 1689 in reference to members of the British political party that opposed the Tories. American Revolution sense of "colonist who opposes Crown policies" is from 1768. Later it was applied to opponents of Andrew Jackson (as early as 1825), and taken as the name of a political party (1834) that merged into the Republican Party in 1854-56.
"... in the spring of 1834 Jackson's opponents adopted the name Whig, traditional term for critics of executive usurpations. James Watson Webb, editor of the New York Courier and Enquirer, encouraged use of the name. [Henry] Clay gave it national currency in a speech on April 14, 1834, likening "the whigs of the present day" to those who had resisted George III, and by summer it was official." [Daniel Walker Howe, "What Hath God Wrought," 2007, p.390]
Whig historian is recorded from 1924. Whig history is "the tendency in many historians ... to emphasise certain principles of progress in the past and to produce a story which is the ratification if not the glorification of the present." [Herbert Butterfield, "The Whig Interpretation of History," 1931]