Online Etymology Dictionary

scuttle (v.1): "scamper, scurry," mid-15c., probably related to scud (q.v.).
scuttle (v.2): "cut a hole in a ship to sink it," 1640s, from skottell (n.) "opening in a ship's deck" (late 15c.), from Middle French escoutille (Modern French écoutille), from Spanish escotilla "hatchway," diminutive of escota "opening in a garment," from escotar "cut out," perhaps from e- "out" + Germanic *skaut-. Figurative use is recorded from 1888.
scuttlebutt (n.): 1805, "water cask kept on a ship's deck," from scuttle "opening in a ship's deck" (see scuttle (v.2)) + butt (n.2) "barrel." Earlier scuttle cask (1777). Meaning "rumor, gossip" first recorded 1901, originally nautical slang, traditionally said to be from sailors' custom of gathering around the scuttlebutt to gossip.
scuzzy (adj.): 1968, North American colloquial, perhaps a blend of scummy and fuzzy. First attested use is in reference to Ratso Rizzo in "Midnight Cowboy."
scythe (n.): Old English siðe, sigði, from Proto-Germanic *segithoz (cf. Middle Low German segede, Middle Dutch sichte, Old High German segensa, German Sense), from PIE root *sek- "cut" (see section (n.)). The sc- spelling crept in early 15c., from influence of Latin scissor "carver, cutter" and scindere "to cut."
scythe (v.): 1590s, from scythe (n.). Related: Scythed; scything.
Scythian: 1540s, from Latin Scythia, from Greek Skythia "ancient region along the north coast of the Black Sea," from Skythes "a Scythian."
sea (n.): Old English sæ "sheet of water, sea, lake," from Proto-Germanic *saiwaz (cf. Old Saxon seo, Old Frisian se, Middle Dutch see), of unknown origin, outside connections "wholly doubtful" [Buck]. Germanic languages also use the general Indo-European word (represented by English mere (n.)), 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. Gothic saiws "lake," marei "sea;" but Dutch zee "sea," meer "lake"). Cf. also Old Norse sær "sea," but Danish sø, usually "lake" but "sea" in phrases. German See is "sea" (fem.) or "lake" (masc.). Meaning "dark area of the moon's surface" is attested from 1660s (see mare (n.2)).

Phrase sea change "transformation" is attested from 1610, first in Shakespeare ("The Tempest," I.ii). Sea anemone is from 1742; sea breeze from 1690s; sea legs is from 1712; sea level from 1806; sea serpent attested from 1640s; sea urchin from 1590s. At sea in the figurative sense of "perplexed" is attested from 1768, from literal sense of "out of sight of land."
sea monkey (n.): 1909 as a heraldic animal, 1964 as a U.S. proprietary name for brine shrimp (Artemia salina), which had been used as food for aquarium fish till they began to be marketed as pets by U.S. inventor Harold von Braunhut (d.2003), who also invented "X-Ray Specs" and popularized pet hermit crabs. He began marketing them in comic book advertisements in 1960 as "Instant Life," and changed the name to Sea Monkeys in 1964, so called for their long tails.
sea-dog (n.): 1590s, "harbor seal," from sea + dog (n.). Meaning "old sailor" is attested from 1840.
sea-horse (n.): late 15c., "walrus," from sea + horse (n.); also see walrus. Main modern sense is attested from 1580s.
sea-lion (n.): c.1600, "kind of lobster," from sea + lion. Later "a fabulous animal" (in heraldry, etc.), 1660s. Applied from 1690s to various species of large eared seals. As code name for the planned German invasion of Britain, it translates German Seelöwe, announced by Hitler July 1940, scrubbed October 1940.
Seabee (n.): 1942, from pronunciation of C.B., abbreviation of Construction Battalion, formed as a volunteer branch of the Civil Engineer Corps of the U.S. Navy.
seacoal (n.): old name for "mineral coal" (as opposed to charcoal), mid-13c.; earlier, in Old English, "jet," which chiefly was found washed ashore by the sea. The coal perhaps so called from resemblance to this, or because it was first dug from beds exposed by wave erosion. From sea + coal.
seafarer (n.): 1510s, from sea + agent noun from fare (n.). The Anglo-Saxon poem now known by that name originally was untitled.
seafaring (adj.): c.1200, from sea + faring (see fare (v.)).
seafood (n.): "food obtained from the sea," 1836, American English, from sea + food.
seagull (n.): 1540s, from sea + gull (n.).
seal (n.1): "design stamped on wax," early 13c., from Old French seel (Modern French sceau), from Vulgar Latin *sigellum (source of Italian suggello, Spanish sello; also Old Frisian and Middle High German sigel, German Siegel), from Latin sigillum "small picture, engraved figure, seal," diminutive of signum "mark, token" (see sign). An earlier borrowing directly from Latin is represented by Old English insigel.
seal (n.2): mammal with flippers, Old English seolh "seal," from Proto-Germanic *selkhaz (cf. Old Norse selr, Swedish sjöl, Middle Low German sel, Middle Dutch seel, Old High German selah), of unknown origin, perhaps a borrowing from Finnic. Seal point "dark brown marking on a Siamese cat" is recorded from 1934, from the dark brown color of seal fur; cf. seal brown "rich, dark brown color," by 1875.
seal (v.): "to fasten with (or as with) a seal," early 13c., from seal (n.1). Meaning "to place a seal on (a document)" is recorded from mid-14c.; sense of "to close up with wax, lead, cement, etc." is attested from 1660s, from the notion of wax seals on envelopes. Related: Sealed; sealing. Sealing-wax is attested from c.1300. To seal one's fate (1810) probably reflects the notion of a seal on an execution warrant.
sealant (n.): 1945, from seal (v.) + -ant.
seam (n.): Old English seam, from Proto-Germanic *saumaz (cf. Old Norse saumr, Old High German soum, German Saum), from PIE root *siw-/*sju- "to sew" (cf. Old English siwian, Latin suere, Sanskrit syuman; see sew).
Chidynge and reproche vnsowen the semes of freendshipe in mannes herte. [Chaucer, "Parson's Tale," c.1386]
Meaning "raised band of stitching on a ball" is recorded from 1888. Geological use is from 1590s.
seaman (n.): "a sailor," Old English sæmanna (plural); see sea + man (n.). Cf. Dutch zeeman, German Seemann, Old Norse sjomaðr.
seamless (adj.): late 15c., from seam + -less. Figurative sense of "whole, integrated" is attested from 1862. Related: Seamlessly; seamlessness.
seamount (n.): by 1908, from sea + mount (n.).
seamstress (n.): 1640s, with -ess + Old English seamestre "person whose work is sewing," from seam. Originally indicating a woman, but the fem. ending -estre no longer was felt as such in late Middle English and a new one added.
seamy (adj.): c.1600, in figurative phrase seamy side "least pleasant, worst," from seam + -y (2); the seamy side of a sewn garment being the less attractive, and thus typically turned in. The popularity of the figurative sense likely is due to its use by Shakespeare in "Othello" IV.ii.146: "Some such Squire he was That turn'd your wits the seamy-side without, And made you to suspect me with the Moore."
Sean: masc. proper name, also Shaun Shawn; Irish form of John.
seance (n.): 1789, "sitting, session," as of a learned society, from French séance "a sitting," from seoir "to sit," from Latin sedere (see sedentary). Meaning "spiritualistic session" first recorded 1845.
seaplane (n.): 1913, from sea + plane (n.2).
seaport (n.): 1590s, from sea + port (n.1).
sear (v.): Old English searian "dry up, to whither," from Proto-Germanic *saurajan, from root of sear "dried up, withered" (see sere). Meaning "to brand, to burn by hot iron" is recorded from 1520s; figurative use is from 1580s. Related: Seared; searing.
search (v.): early 14c., from Old French cerchier "to search," from Latin circare "go about, wander, traverse," in Late Latin "to wander hither and thither," from circus "circle" (see circus). Phrase search me as a verbal shrug of ignorance first recorded 1901. Search warrant first attested 1739. Search engine attested from 1988. Search and destroy as a modifier is 1966, American English, from the Vietnam War. Search and rescue is from 1944.
search (n.): early 15c., "right to investigate illegal activity; examination of records, wills, etc.; a search through an area or a place," from Old French cherche, from cerchier (see search (v.)).
searchlight (n.): also search-light, 1883, from search (v.) + light (n.).
seashell (n.): also sea-shell, Old English sæscel (see sea and shell (n.)).
seashore (n.): 1520s, from sea + shore (n.). Commonly defined in law as the ground between the ordinary high and low water-marks.
seasick (adj.): 1560s, from sea + sick (n.). Related: Seasickness.
seaside (n.): c.1200, from sea + side (n.). As an adjective from 1781.
season (n.): c.1300, "a period of the year," with reference to weather or work, from Old French seison (Modern French saison) "a sowing, planting," from Latin sationem (nominative satio) "a sowing," from past participle stem of serere "to sow" (see sow). Sense shifted in Vulgar Latin from "act of sowing" to "time of sowing." In Old French and Old Provençal this was extended to "season" in general (sowing season being the most important). Season ticket is attested from 1820.
season (v.): "improve the flavor of by adding spices," c.1300, from Old French assaisoner "to ripen, season," from root of season (n.) on the notion of fruit becoming more palatable as it ripens. Applied to timber by 1540s. In 16c., it also meant "to copulate with." Related: Seasoned. Seasoning (n.) is from 1570s.
seasonable (adj.): late 14c., from season (n.) + -able. Related: Seasonably.
seasonal (adj.): 1838, from season + -al (1). Of workers or employment, from 1904. Related: Seasonally.
seat (n.1): "thing to sit on, act of sitting," c.1200, from Old Norse sæti "seat, position," from Proto-Germanic *sæt- (cf. Old High German saze, Middle Dutch gesaete "seat," Old High German gisazi, German Gesäß "buttocks"), from PIE root *sed- "to sit" (see sit). Meaning "posterior of the body" (the sitting part) is from c.1600; sense of "part of a garment which covers the buttocks" is from 1835. Seat belt is from 1932, originally in airplanes.
seat (n.2): "residence, abode, established place," late 13c., extended use of seat (n.1), influenced by Old French siege "seat, established place," and Latin sedes "seat." Meaning "city in which a government sits" is attested from c.1400. Sense of "place in a parliament or other legislative body" is attested from 1774. Old English had sæt "place where one sits in ambush," which also meant "residents, inhabitants," and is the source of the -set in Dorset and Somerset.
seat (v.): 1570s, from seat (n.1). Related: Seated; seating.
SEATO: 1954, acronym for Southeast Asia Treaty Organization.
Seattle: city founded 1853, named for Seatlh (c.1790-1866), native chief who befriended white settlers. His name is in the Salishan tongue.
seavy: 1680s, from seave "rush" (c.1400), from Old Norse sef.