singly (adv.) Look up singly at Dictionary.com
c.1300, from single (adj.) + -ly (2).
singspiel (n.) Look up singspiel at Dictionary.com
1876, from German Singspiel, literally "a singing play," from singen "to sing" (see sing (v.)) + Spiel "a play" (see spiel). Kind of performance popular in Germany late 18c.
singular (adj.) Look up singular at Dictionary.com
mid-14c., "alone, apart; being a unit; special, unsurpassed," from Old French singuler "personal particular; distinctive; singular in number" (12c., Modern French singulier) or directly from Latin singularis "single, solitary, one by one, one at a time; peculiar, remarkable," from singulus (see single (adj.)). Meaning "remarkably good, unusual, rare, separated from others (by excellence), uncommon" is from c.1400 in English; this also was a common meaning of Latin singularis.
singularity (n.) Look up singularity at Dictionary.com
c.1400, "unusual behavior," also "singleness of aim or purpose," from Old French singulerte "peculiarity" (12c., Modern French singularité) or directly from Late Latin singularitatem (nominative singularitas) "a being alone," from singularis (see singular (adj.)). Meaning "fact of being different from others" is c.1500. Mathematical sense of "point at which a function takes an infinite value" is from 1893. Astronomical use is from 1965.
singularly (adv.) Look up singularly at Dictionary.com
late 14c., "exclusively, alone, solely; uniquely; individually; in an unusual way, especially," from singular + -ly (2).
singultus (n.) Look up singultus at Dictionary.com
Latin, "a sob; a speech broken by sobs."
Sinhalese (adj.) Look up Sinhalese at Dictionary.com
also Singhalese, "pertaining to Sri Lanka," 1797, from Sanskrit Sinhala "Sri Lanka, Ceylon," from simhala-, literally "of lions," from simhah "lion." As the name of a language spoken there, it is attested from 1801.
Sinic (adj.) Look up Sinic at Dictionary.com
"Chinese," 1660s, from Medieval Latin Sinicus, from Sina "China," from Late Latin Sinae (plural) "the Chinese" (see Sino-).
sinical (adj.) Look up sinical at Dictionary.com
"of or relating to sines," 1590s, from sine + -ical.
Sinicism (n.) Look up Sinicism at Dictionary.com
"Chinese ways, Chinese affectations," 1891; see Sino- + -ism. Related: Sinicize; Sinification.
sinister (adj.) Look up sinister at Dictionary.com
early 15c., "prompted by malice or ill-will, intending to mislead," from Old French senestre, sinistre "contrary, false; unfavorable; to the left" (14c.), from Latin sinister "left, on the left side" (opposite of dexter), of uncertain origin. Perhaps meaning properly "the slower or weaker hand" [Tucker], but Klein and Buck suggest it's a euphemism (see left (adj.)) connected with the root of Sanskrit saniyan "more useful, more advantageous." With contrastive or comparative suffix -ter, as in dexter (see dexterity).

The Latin word was used in augury in the sense of "unlucky, unfavorable" (omens, especially bird flights, seen on the left hand were regarded as portending misfortune), and thus sinister acquired a sense of "harmful, unfavorable, adverse." This was from Greek influence, reflecting the early Greek practice of facing north when observing omens. In genuine Roman auspices, the augurs faced south and left was favorable. Thus sinister also retained a secondary sense in Latin of "favorable, auspicious, fortunate, lucky."

Meaning "evil" is from late 15c. Used in heraldry from 1560s to indicate "left, to the left." Bend (not "bar") sinister in heraldry indicates illegitimacy and preserves the literal sense of "on or from the left side" (though in heraldry this is from the view of the bearer of the shield, not the observer of it).
sinistral (adj.) Look up sinistral at Dictionary.com
late 15c., "unlucky," from Old French senestral, sinistral or Medieval Latin *sinistralis, from sinister (see sinister). Meaning "on the left side" is from 1803. Related: Sinistrally.
sinistrorse (adj.) Look up sinistrorse at Dictionary.com
1856, a word wanted by the botanists to describe the direction of spiral structures in nature, from Latin sinistrorsus "toward the left side," from sinister "left" (see sinister). It was paired with dextrorse but confusion over what was the proper point of view to reckon leftward or rightward spiraling prevented the word being as useful as it might have been.
sink (v.) Look up sink at Dictionary.com
Old English sincan (intransitive) "become submerged, go under, subside" (past tense sanc, past participle suncen), from Proto-Germanic *senkwan (cognates: Old Saxon sinkan, Old Norse sökkva, Middle Dutch sinken, Dutch zinken, Old High German sinkan, German sinken, Gothic sigqan), from PIE root *sengw- "to sink."

The transitive use (mid-13c.) supplanted Middle English sench (compare drink/drench) which died out 14c. Related: Sank; sunk; sinking. Sinking fund is from 1724. Adjective phrase sink or swim is from 1660s. To sink without a trace is World War I military jargon, translating German spurlos versenkt.
sink (n.) Look up sink at Dictionary.com
early 15c., "cesspool, pit for reception of wastewater or sewage," from sink (v.). Figurative sense of "place where corruption and vice abound" is from 1520s. Meaning "drain for carrying water to a sink" is from late 15c. Sense of "shallow basin (especially in a kitchen) with a drainpipe for carrying off dirty water" first recorded 1560s. In science and technical use, "place where heat or other energy is removed from a system" (opposite of source), from 1855.
sinker (n.) Look up sinker at Dictionary.com
1838 in the fishing-line sense, agent noun from sink (v.).
sinkhole (n.) Look up sinkhole at Dictionary.com
also sink-hole, mid-15c., "sewage pit," from sink (n.) + hole (n.). As a geological phenomenon, "hole made in the earth in limestone regions by underground erosion," 1780, from sink (v.).
sinless (adj.) Look up sinless at Dictionary.com
Old English synleas; see sin (n.) + -less. Related: Sinlessly; sinlessness.
Sinn Fein (n.) Look up Sinn Fein at Dictionary.com
1905, from Irish, literally "we ourselves," from Old Irish féin "self," from PIE *swei-no-, suffixed form of root *s(w)e- (see idiom). Movement founded 1905 by Irish journalist and politician Arthur Griffith (1872-1922).
sinner (n.) Look up sinner at Dictionary.com
mid-14c., agent noun from sin (v.). Old English had synngiend in this sense.
Sino- Look up Sino- at Dictionary.com
before vowels Sin-, word-forming element meaning "Chinese," 1879, from Late Latin Sinæ (plural) "the Chinese," from Ptolemaic Greek Sinai, from Arabic Sin "China," probably from Chinese Ch'in, name of the fourth dynasty of China (see China).
Sinologist (n.) Look up Sinologist at Dictionary.com
1814; see Sino- + -logy + -ist. Related: Sinology (1834).
Sinon Look up Sinon at Dictionary.com
name of the Greek who induced the Trojans to take the wooden horse into the city; hence "a deceiver by false tales."
Sinophobe (n.) Look up Sinophobe at Dictionary.com
1919, from Sino- + phobe. Related: Sinophobic; Sinophobia (1876).
sinsemilla (n.) Look up sinsemilla at Dictionary.com
potent strain of marijuana, 1975, from Mexican Spanish, literally "without seed," from Latin sine "without" (see sans) + semen "seed" (see semen).
sinter (n.) Look up sinter at Dictionary.com
1780, from German Sinter, cognate with English cinder.
sinuate (adj.) Look up sinuate at Dictionary.com
1680s, from Latin sinuatus, past participle of sinuare (see insinuate).
sinuous (adj.) Look up sinuous at Dictionary.com
"full of turns and curves," 1570s, from Latin sinuosus "full of curves, folds, or bendings," from sinus "curve, fold, bend" (see sinus). Related: Sinuously; sinuousness.
sinus (n.) Look up sinus at Dictionary.com
"hollow curve or cavity in the body," early 15c., from Medieval Latin sinus, from Latin sinus "bend, fold, curve, a bent surface; a bay, bight, gulf; a fold in land;" also "fold of the toga about the breast," hence "bosom," and figuratively "love, affection, intimacy; interior, inmost part;" of unknown origin.
sinusitis (n.) Look up sinusitis at Dictionary.com
"inflammation of the sinuses," 1896; see sinus + -itis.
sinusoid Look up sinusoid at Dictionary.com
1823 in mathematics; 1900 in physiology, from sinus + -oid. Related: Sinusoidal.
Siouan (adj.) Look up Siouan at Dictionary.com
1885, from Sioux + -an. Replacing Dakotan.
Sioux Look up Sioux at Dictionary.com
group of North American Indian tribes, 1761, from North American French, short for Nadouessioux, sometimes said to be from Ojibway (Algonquian) Natowessiwak (plural), literally "little snakes," from nadowe "Iroquois" (literally "big snakes"). Another explanation traces it to early Ottawa (Algonquian) singular /na:towe:ssi/ (plural /na:towe:ssiwak/) "Sioux," apparently from a verb meaning "to speak a foreign language" [Bright]. In either case, a name given by their neighbors; the people's name for themselves is Dakota.
sip (v.) Look up sip at Dictionary.com
late 14c., of uncertain origin, perhaps from a source related to Low German sippen "to sip," or from Old English sypian "absorb, drink in," related to supan "to take into the mouth a little at a time" (see sup (v.2)). Related: Sipped; sipping.
sip (n.) Look up sip at Dictionary.com
c.1500, from sip (v.).
siphon (n.) Look up siphon at Dictionary.com
late 14c., from Latin sipho (genitive siphonis) "a siphon," from Greek siphon "pipe, tube for drawing wine from a cask," of unknown origin. Related: Siphonal.
siphon (v.) Look up siphon at Dictionary.com
1859, from siphon (n.). Figurative sense of "to draw off, divert" is recorded from 1940. Related: Siphoned; siphoning.
sir Look up sir at Dictionary.com
c.1300, title of honor of a knight or baronet (until 17c. also a title of priests), variant of sire, originally used only in unstressed position. Generalized as a respectful form of address by mid-14c.; used as a salutation at the beginning of letters from early 15c.
sire (v.) Look up sire at Dictionary.com
"to beget, to be the sire of," 1610s, from sire (n.). Used chiefly of beasts, especially of stallions. Related: Sired; siring.
sire (n.) Look up sire at Dictionary.com
c.1200, title placed before a name and denoting knighthood, from Old French sire "lord (appellation), sire, my lord," from Vulgar Latin *seior, from Latin senior "older, elder" (see senior (adj.)). Standing alone and meaning "your majesty" it is attested from early 13c. General sense of "important elderly man" is from mid-14c.; that of "father, male parent" is from mid-13c.
siren (n.) Look up siren at Dictionary.com
mid-14c., "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 Seirenes, 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."

Meaning "device that makes a warning sound" (on an ambulance, etc.) first recorded 1879, in reference to steamboats, perhaps from similar use of the French word. Figurative sense of "one who sings sweetly and charms" is recorded from 1580s. The classical descriptions of them were mangled in medieval translations and glosses, resulting in odd notions of what they looked like.
Sirius (n.) Look up Sirius at Dictionary.com
brightest star by magnitude, late 14c., from Latin Sirius "the Dog Star," from Greek Seirios, said to mean literally "scorching" or "the scorcher." But other related Greek words seem to derive from this use, and the name might be a folk-etymologized borrowing from some other language. An Egyptian name for it was Sothis. The connection of the star with scorching heat is from its ancient heliacal rising at the summer solstice (see dog days). Also see dog star. Related: Sirian. The constellation Canis Major seems to have grown from the star, not the other way.
Homer made much of it as [Kyon], but his Dog doubtless was limited to the star Sirius, as among the ancients generally till, at some unknown date, the constellation was formed as we have it, -- indeed till long afterwards, for we find many allusions to the Dog in which we are uncertain whether the constellation or its lucida is referred to. [Richard Hinckley Allen, Canis Major in "Star Names and Their Meanings," London: 1899]
sirloin (n.) Look up sirloin at Dictionary.com
early 15c., surloine, from Middle French surlonge, literally "upper part of the loin," from sur "over, above" (see sur-) + longe "loin," from Old French loigne (see loin).

English spelling with sir- dates from 1620s, by folk-etymology supposed to be because the cut of beef was "knighted" by an English king for its superiority, a tale variously told of Henry VIII, James I, and Charles II. The story dates to 1655.
sirocco (n.) Look up sirocco at Dictionary.com
"hot wind blowing from the Libyan deserts," 1610s, from Italian sirocco, from vulgar Arabic shoruq "the east wind," from Arabic sharqi "eastern, east wind," from sharq "east," from sharaqa "to rise" (in reference to the sun).
sirrah Look up sirrah at Dictionary.com
1520s, term of address used to men or boys expressing anger or contempt, archaic extended form of sir (in U.S., siree, attested from 1823).
sis (n.) Look up sis at Dictionary.com
1650s, abbreviated form of sister; in American English, applied generally to girls and young women (1859). It also was the familiar short form of Cecilie, Cicely, a common name for girls in the Middle English period.
sis-boom-bah Look up sis-boom-bah at Dictionary.com
cheerleading chant, originally (1867) an echoic phrase imitating the sound of a skyrocket flight (sis), the burst of the fireworks (boom), and the reaction of the crowd ((b)ah).
sisal (n.) Look up sisal at Dictionary.com
1883, short for Sisal hemp or grass (1843), from Sisal, port in Yucatan, from which the rope-making fiber was exported.
sissify (v.) Look up sissify at Dictionary.com
1897 (implied in sissified), American English, from sissy + -fy. Related: Sissifying; sissification (1915).
sissy (n.) Look up sissy at Dictionary.com
1846, "sister," extended form of sis (q.v.). Meaning "effeminate man" is recorded from 1887; the adjective in this sense is from 1891. Related: Sissiness. Sissy bar is recorded from 1969.