Online Etymology Dictionary

syllabic (adj.): 1728, from Modern Latin syllabicus, from Greek syllabikos, from syllabe (see syllable).
syllable (n.): late 14c., from Anglo-French sillable, Old French sillabe, from Latin syllaba, from Greek syllabe "a syllable, several sounds or letters taken together," literally "a taking together," from syn- "together" (see syn-) + stem of lambanein "to take" (see analemma). The extra -l- was added by analogy with participle and principle.
syllabus (n.): 1650s, "table of contents of a series of lectures, etc.," from Late Latin syllabus "list," a misreading of Greek sittybos (plural of sittyba "parchment label, table of contents," of unknown origin) in a 1470s edition of Cicero's "Ad Atticum" iv.5 and 8. The proper plural would be syllabi.
syllepsis (n.): from Late Latin syllepsis, from Greek syn "together" (see syn-) + lepsis "a taking," related to lambanein (see analemma).
syllogism (n.): late 14c., from Old French silogisme "a syllogism," from Latin syllogismus, from Greek syllogismos "a syllogism," originally "inference, conclusion, computation, calculation," from syllogizesthai "bring together, premise, conclude," literally "think together," from syn- "together" (see syn-) + logizesthai "to reason, count," from logos "a reckoning, reason" (see logos).
syllogistic (adj.): 1660s, from Latin syllogisticus or directly from Greek syllogistikos, from syllogizesthai (see syllogism).
sylph (n.): 1650s, from Modern Latin sylphes (plural), coined 16c. by Paracelsus (1493-1541), originally referring to any race of spirits inhabiting the air, described as being mortal but lacking a soul. Paracelsus' word seems to be an arbitrary coinage, but perhaps it holds a suggestion of Latin sylva and Greek nymph. The meaning "slender, graceful girl" first recorded 1838, on the notion of "light, airy movements." Silphid (1670s) are the younger or smaller variety, from French sylphide (1670s).
sylvan (adj.): "of the woods," 1570s; earlier as a noun (1560s), "deity of the woods," from Middle French sylvain, from Latin silvanus "pertaining to wood or forest" (originally only in silvanae "goddesses of the woods"), from silva "wood, forest, grove," of unknown origin. Silvanus was used by the Romans as the proper name of a god of woods and fields, identified with Pan. Spelling with -y- influenced by Greek hyle "forest," from which the Latin word was supposed to derive.
Sylvester: masc. proper name, from Latin, literally "woody, sylvan, rural," from Latin silvester, from Latin silva "wood, forest" (see sylvan). St. Sylvester's Day is Dec. 31.
Sylvia: fem. proper name, literally "inhabiting woods," from Latin silva "wood, forest" (see sylvan).
Symbionese (adj.): as in Symbionese Liberation Army, name adopted by a socialist revolutionary group active in U.S. c.1972-76, coined from symbiosis + people-name ending -ese.
symbiosis (n.): 1877, as a biological term, "mutually beneficial association of two different organisms," from Modern Latin, from Greek symbiosis "a living together," from symbioun "live together," from symbios "(one) living together (with another), partner," from syn- "together" (see syn-) + bios "life" (see bio-). Given a wider (non-biological) sense by 1921. An earlier sense of "communal or social life" is found in 1620s.
symbiotic (adj.): 1882, in biology, from symbiosis. Of human activities, from 1951.
symbol (n.): early 15c., "creed, summary, religious belief," from Late Latin symbolum "creed, token, mark," from Greek symbolon "token, watchword" (applied c.250 by Cyprian of Carthage to the Apostles' Creed, on the notion of the "mark" that distinguishes Christians from pagans), literally "that which is thrown or cast together," from syn- "together" (see syn-) + bole "a throwing, a casting, the stroke of a missile, bolt, beam," from bol-, nominative stem of ballein "to throw" (see ballistics). The sense evolution in Greek is from "throwing things together" to "contrasting" to "comparing" to "token used in comparisons to determine if something is genuine." Hence, "outward sign" of something. The meaning "something which stands for something else" first recorded 1590 (in "Faerie Queene").
symbolic (adj.): c.1600 (implied in symbolically); see symbol + -ic.
symbolism (n.): 1650s, "practice of representing things with symbols," from symbol + -ism. Attested from 1892 as a movement in French literature that aimed at representing ideas and emotions by indirect suggestion rather than direct expression; rejecting realism and naturalism, it attached symbolic meaning to certain objects, words, etc. French symboliste was coined by poet Paul Verlaine (1844-1896) in 1885.
symbolize (v.): c.1600, "to represent by a symbol," also "to be a symbol of," from French symboliser, from Modern Latin symbolizare, from symbolum (see symbol). Related: Symbolized; symbolizes; symbolizing.
symbology (n.): 1840, from Modern Latin symbolia (from Greek symbolon; see symbol) + -ology.
symmetric (adj.): 1796, from symmetry + -ic.
symmetrical (adj.): 1570s (implied in symmetrically), from symmetry + -ical.
symmetry (n.): 1560s, "relation of parts, proportion," from Latin symmetria, from Greek symmetria "agreement in dimensions, due proportion, arrangement," from symmetros "having a common measure, even, proportionate," from syn- "together" (see syn-) + metron "meter" (see meter (n.2)). Meaning "harmonic arrangement of parts" first recorded 1590s. Symmetrophobia is from 1809, supposed to be evident in Egyptian temples and Japanese art.
sympathetic (adj.): 1640s, "pertaining to sympathy," from Modern Latin sympatheticus, from Greek sympathetikos, from sympathein, from sympathes "having a fellow feeling, affected by like feelings" (see sympathy). Meaning "having fellow feeling" is recorded from 1718. In anatomical sense, the word is attested from 1769, from Modern Latin (nervus) sympathicus, coined by Jacques-Benigne Winslow (1669-1760), Danish anatomist living in Paris. Related: Sympathetically.
sympathise (v.): chiefly British English spelling of sympathize (q.v.); for suffix, see -ize. Related: Sympathised; sympathising.
sympathize (v.): "to have fellow-feeling," c.1600; see sympathy + -ize. Related: Sympathized; sympathizing.
sympathizer (n.): 1815, agent noun from sympathize.
sympathy (n.): 1570s, "affinity between certain things," from Middle French sympathie, from Late Latin sympathia "community of feeling, sympathy," from Greek sympatheia, from sympathes "having a fellow feeling, affected by like feelings," from syn- "together" (see syn-) + pathos "feeling" (see pathos). In English, almost a magical notion at first; e.g. in reference to medicines that heal wounds when applied to a cloth stained with blood from the wound. Meaning "conformity of feelings" is from 1590s; sense of "fellow feeling" is first attested 1660s. An Old English loan-translation of sympathy was efensargung.
sympatric (adj.): 1904, from syn- + Greek patra "fatherland." Opposite of allopatric.
symphonic (adj.): 1854 (implied in symphonically); see symphony + -ic.
symphony (n.): late 13c., the name of various musical instruments, from Old French symphonie "harmony" (12c.), from Latin symphonia "a unison of sounds, harmony," from Greek symphonia "harmony, concert," from symphonos "harmonious," from syn- "together" (see syn-) + phone "voice, sound" (see fame (n.)).

Meaning "harmony of sounds" is attested from mid-15c.; sense of "music in parts" is from 1590s. "It was only after the advent of Haydn that this word began to mean a sonata for full orchestra. Before that time it meant a prelude, postlude, or interlude, or any short instrumental work." ["Elson's Music Dictionary"] Meaning "elaborate orchestral composition" first attested 1789 (symphonic in this sense is from 1864). Elliptical for "symphony orchestra" from 1926.
symphysis (n.): Modern Latin, from Greek symphysis "a growing together," from syn "together" (see syn-) + physis "growth" (see physics).
symposium (n.): 1580s, "account of a gathering or party," from Latin symposium "drinking party, symposium," from Greek symposion "convivial gathering of the educated" (related to sympotes "drinking companion"), from syn- "together" (see syn-) + posis "a drinking," from a stem of Aeolic ponen "to drink," cognate with Latin potare "to drink" (see potion). The sense of "meeting on some subject" is from 1784. Reflecting the Greek fondness for mixing wine and intellectual discussion, the modern sense is especially from the word being used as a title for one of Plato's dialogues. Greek plural is symposia, and the leader of one is a symposiarch (c.1600 in English).
symptom (n.): 1540s, earlier sinthoma (late 14c.), from Medieval Latin sinthoma "symptom of a disease," from Late Latin symptoma, from Greek symptoma (genitive symptomatos) "a happening, accident, disease," from stem of sympiptein "to befall," from syn- "together" (see syn-) + piptein "to fall," from PIE *pi-pt-, reduplicated form of root *pet- "to rush; to fly" (see petition (n.)). Spelling altered in English by influence of Middle French and Late Latin forms. Symptomatic in general sense of "indicative (of)" is from 1751.
symptomatic (adj.): 1690s, from French symptomatique or directly from Late Latin symptomaticus, from symptomat-, stem of symptoma (see symptom). Related: Symptomatical (1580s).
symptomatology (n.): 1798, from Modern Latin symptomatologia, from symptomat-, stem of symptoma (see symptom) + -logia (see -logy).
symptomology (n.): 1868, shortening of symptomatology.
syn-: word-forming element meaning "together with," from Greek syn "with, together with," of unknown origin.
synaesthesia (n.): also synesthesia, "sensation in one part of the body produced by stimulus in another," 1881, in some cases via French, from Modern Latin, from Greek syn- "together" (see syn-) + stem aisthe "to feel, perceive." Also psychologically, of the senses (colors having an odor, etc.), from 1891.
synagogue (n.): late 12c., from Old French sinagoge (11c.), from Late Latin synagoga "congregation of Jews," from Greek synagoge "place of assembly, synagogue," literally "meeting, assembly," from synagein "to gather, assemble," from syn- "together" (see syn-) + agein "bring, lead" (see act). Used by Greek translators of the Old Testament as a loan-translation of late Hebrew keneseth "assembly" (cf. beth keneseth "synagogue," literally "house of assembly.")
synapse (n.): "junction between two nerve cells," 1899, from Greek synapsis "conjunction," from synaptein "to clasp," from syn- "together" (see syn-) + haptein "to fasten." Related to apse. Introduced by English physiologist Sir Michael Foster (1836-1907) at the suggestion of English classical scholar Arthur Woollgar Verral (1851-1912).
synapsis (n.): plural synapses, 1895 in biology, Modern Latin, from Greek synapsis "connection, junction" (see synapse).
synaptic (adj.): 1895, used as an adj. corresponding to synapsis, from Greek synaptikos, literally "connective, copulative."
sync: 1929, shortened form of synchronization (see synchronize). Originally in reference to soundtracks and pictures in the movies. Sense of "be in agreement, coincide" first recorded 1961 in in sync.
synchronic (adj.): 1833 shortening of synchronical (1650s), from Late Latin synchronus "simultaneous" (see synchronous). Linguistic sense is first recorded 1922, probably a borrowing from French synchronique (de Saussure, 1913).
synchronicity (n.): 1953; from synchronic + -ity. Originally in Jung.
synchronism (n.): 1580s, "quality of being synchronous," from Modern Latin synchronismus, from Greek synchronismos, from synchronos (see synchronous). Meaning "recurring at the same successive instants of time" is from 1854.
synchronize (v.): 1620s, "to occur at the same time," from Greek synchronizein "be of the same time," from synchronos "happening at the same time" (see synchronous). The sense of "make synchronous" is first recorded 1806. Synchronized swimming is recorded from 1950.
synchronous (adj.): 1660s, "existing or happening at the same time," from Late Latin synchronus "simultaneous," from Greek synchronos "happening at the same time," from syn- "together" (see syn-) + khronos "time" (see chrono-). Meaning "recurring at the same successive instants of time" is attested from 1670s.
synchrony (n.): 1848, from Greek synkhronos (see synchronous) + -y (2).
synclinal (adj.): "sloping downward on both sides," 1833 (in Lyell), from Greek synklinein "to incline, lean," from syn- "together" (see syn-) + klinein "to slope" (see lean (v.)).
syncline (n.): 1873, back-formation from synclinal.