Online Etymology Dictionary

symptomatic (adj.): 1690s, from French symptomatique or directly from Late Latin symptomaticus, from symptomat-, stem of symptoma (see symptom). General sense of "indicative (of)" is from 1751. Related: Symptomatical (1580s).
symptomatology (n.): study of symptoms, 1737, from medical Latin symptomatologia, from symptomat-, stem of symptoma (see symptom) + -logia (see -logy). Related: Symptomatological.
symptomology (n.): 1830, shortening of symptomatology.
syn-: word-forming element meaning "together with, jointly; alike; at the same time," also sometimes completive or intensive, from Greek syn (prep.) "with, together with, along with, in the company of," from PIE *ksun- "with" (source also of Russian so- "with, together," from Old Russian su(n)-). Assimilated to -l-, reduced to sy- before -s- and -z-, and altered to sym- before -b-, -m- and -p-. Since 1970s also with a sense of "synthetic."
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-) + aisthesis "feeling" (from PIE root *au- "to perceive;" see audience) + abstract noun ending -ia. Also psychologically, of the senses (colors that seem to the perceiver to having odor, etc.), from 1891. Related: Synaesthetic (adj.).
synagogue (n.): late 12c., "the regular public worship of the Jews," also the building in which this is done, from Old French sinagoge "synagogue, mosque, pagan temple" (11c., Modern French synagogue), from Late Latin synagoga "congregation of Jews," from Greek synagoge "place of assembly, synagogue; meeting, assembly," literally "a bringing together," from synagein "to gather, bring together, assemble," from syn- "together" (see syn-) + agein "bring, lead" (see act (v.)).

Used by Greek translators of the Old Testament as a loan-translation of late Hebrew keneseth "assembly" (as in beth keneseth "synagogue," literally "house of assembly;" compare Knesset). Related: Synagogical; synagogal.
synallagmatic (adj.): "expressing reciprocal obligations," from Greek synallagmatikos, from synallagma "a covenant, contract," from syn- "together with" (see syn-) + allagma "thing taken in exchange," from stem of allassein "to exchange, barter," from allos "another" (see alias (adv.)).
synapse (n.): "junction between two nerve cells," 1899, medical Latin, from Greek synapsis "conjunction," from or related to synaptein "to clasp, join together, tie or bind together, be connected with," from syn- "together" (see syn-) + haptein "to fasten" (see 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 cellular biology, Modern Latin, from Greek synapsis "connection, junction" (see synapse).
synaptic (adj.): 1895, used as an adjective corresponding to synapsis, from Greek synaptikos, literally "connective, copulative."
sync (n.): also synch, 1929, shortened form of synchronization (see synchronize). Originally in reference to soundtracks and pictures in the movies. Sense of "synchronization, harmony, agreement" first recorded 1961 in in sync. As a verb, short for synchronize, by 1945.
synchronic (adj.): "occurring at the same time," 1775, 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). Synchronal "simultaneous" is from 1650s. Related: synchronically.
synchronicity (n.): 1953; from synchronic + -ity. Originally in Jung. Synchroneity is from 1889, but equally malformed, and see synchronism.
synchronism (n.): 1580s, "quality of being synchronous," from Modern Latin synchronismus, from Greek synkhronismos, from synkhronos (see synchronous). Meaning "recurring at the same successive instants of time" is from 1854.
synchronization (n.): 1828, noun of action or state from synchronize.
synchronize (v.): 1620s, "to occur at the same time," from Greek synkhronizein "be of the same time," from synkhronos "happening at the same time" (see synchronous). The transitive sense of "make synchronous" is first recorded 1806. Of timepieces by 1879. Related: Synchronized; synchronizing. Synchronized swimming is recorded from 1950.
synchronous (adj.): 1660s, "existing or happening at the same time," from Late Latin synchronus "simultaneous," from Greek synkhronos "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. Related: Synchronously.
synchrony (n.): "occurrence or existence at the same time," 1848, from Greek synkhronos (see synchronous) + -y (2).
synclinal (adj.): "sloping downward on both sides," 1833 (in Lyell), from -al (1) + Latinized form of stem of Greek synklinein "to incline, lean," from syn- "together" (see syn-) + klinein "to slope" (see lean (v.)).
syncline (n.): 1855, back-formation from synclinal.
syncopate (v.): c. 1600, "shorten words by omitting syllables or letters in the middle," back-formation from syncopation, or else from Late Latin syncopatus, past participle of syncopare "to shorten," also "to faint away, to swoon," from Late Latin syncope (see syncope). Musical sense is from 1660s. Related: Syncopated; syncopating.
syncopation (n.): 1530s, "contraction of a word by omission of middle sounds," from Medieval Latin syncopationem (nominative syncopatio) "a shortening or contraction," from past participle stem of syncopare "to shorten," also "to faint away, to swoon," from Late Latin syncope (see syncope). Musical sense is attested from 1590s.
syncope (n.): 1520s, "contraction of a word by omission of middle sounds or letters," from Latin syncope "contraction of a word by elision," from Greek synkope "contraction of a word," originally "a cutting off, cutting up, cutting short," from synkoptein "to cut up," from syn- "together, thoroughly" (see syn-) + koptein "to cut," from PIE root *kop- "to beat, strike" (see hatchet (n.)).

An earlier use of the word in pathology is represented by Middle English syncopis, sincopin "loss of consciousness accompanied by weak pulse" (c. 1400, from Late Latin accusative syncopen); compare Old French syncope "illness, fainting fit" ("failure of the heart's action," hence "unconsciousness"). The spelling of this was re-Latinized 16c. Related: Syncopic; syncoptic.
syncretism (n.): "reconciliation of different beliefs," 1610s, from French syncrétisme (17c.) and directly from Modern Latin syncretismus (used by German Protestant theologian David Pareus, 1615), from Greek synkretismos "union of communities," from synkretizein "to combine against a common enemy," from syn- "together" (see syn-) + second element of uncertain origin. One theory connects it with kretismos "lying," from kretizein "to lie like a Cretan;" another connects it with the stem of kerannynai "to mix, blend;" krasis "mixture." Related: Syncretist; syncretistic.
syncretize (v.): 1670s, from Latinized form of Greek synkretizein (see syncretism). Related: Syncretized; syncretizing.
syncytial (adj.): 1895, "pertaining to a syncytium" (1877), Modern Latin, from Greek syn "together" (see syn-) + kytos "receptacle, vessel," used in biology for "cell" (see cyto-).
syndetic (adj.): "connecting," 1874, from -ic + Greek syndetos "bound together," adjective of syndein (see asyndeton).
syndic (n.): c. 1600, "a civil magistrate, especially in Geneva," from French syndic "chief representative" (14c.), from Late Latin syndicus "representative of a group or town," from Greek syndikos "public advocate," as an adjective, "belonging jointly to," from syn- "together" (see syn-) + dike "judgment, justice, usage, custom" (cognate with Latin dicere "to show, tell;" see diction). Meaning "accredited representative of a university or other corporation" first found c. 1600. Related: Syndical.
syndicalism (n.): 1907, from French syndicalisme "movement to transfer ownership of means of production and distribution to industrial workers," from syndical "of a labor union," from syndic "chief representative" (see syndic).
"Syndicalism" is in France the new, all-absorbing form of Labor's conflict with Capital. Its growth has been so rapid that its gravity is not appreciated abroad. This year, even more than last, the strikes and other "direct action," which it has combined, have upset the industrial life of the country, and forced the attention of Parliament and Government. ["The Nation," June 20, 1907]
syndicate (n.): 1620s, "council or body of representatives," from French syndicat (15c.), from syndic "representative of a corporation" (see syndic) + -at (see -ate (1)). Meaning "combination of capitalists or companies to carry out some commercial undertaking" first occurs 1865. Publishing sense of "association of publishers for purchasing articles, etc., for simultaneous publication in a number of newspapers" is from 1889. As a synonym for "organized crime, the Mob" it is recorded from 1929.
syndicate (v.): 1889, "form into a syndicate," from syndicate (n.). Meaning "sell for simultaneous publication" is from 1889. Earlier it meant "to judge, censure" (1610s), from Medieval Latin syndicatus, past participle of syndicare. Related: Syndicated; syndicating.
syndication (n.): 1887, "act of forming a syndicate," from syndicate (n.) + -ion. Sense of "publication, broadcast, or ownership by a syndicate" is attested from 1925.
syndrome (n.): "a number of symptoms occurring together," 1540s, from medical Latin, from Greek syndrome "concurrence of symptoms, concourse of people," from syndromos "place where several roads meet," literally "a running together," from syn- "with" (see syn-) + dromos "a running, course" (see dromedary). Psychological sense is from 1955.
syne (adv.): in Burns' poem "Auld Lang Syne" (1788), Scottish form of since (q.v.), without the adverbial genitive inflection, recorded from c. 1300.
synecdoche (n.): "figure of speech in which a part is taken for the whole or vice versa," late 15c. correction of synodoches (late 14c.), from Medieval Latin synodoche, alteration of Late Latin synecdoche, from Greek synekdokhe "the putting of a whole for a part; an understanding one with another," literally "a receiving together or jointly," from synekdekhesthai "supply a thought or word; take with something else, join in receiving," from syn- "with" (see syn-) + ek "out" (see ex-) + dekhesthai "to receive," related to dokein "seem good" (see decent). Typically an attribute or adjunct substituted for the thing meant ("head" for "cattle," "hands" for "workmen," "wheels" for "automobile," etc.). Compare metonymy. Related: Synecdochical.
synechia (n.): plural synechiae, "morbid union of parts, especially of the eye," 1842, medical Latin, from Greek synekheia "continuity," from synekhes "continuous," from syn "together" (see syn-) + ekhein "to hold" (see scheme (n.)).
synergetic (adj.): "working together, cooperating," 1680s, from Greek synergetikos "cooperative," from synergein "to work together, cooperate" (see synergy). Synergic (1849) is from synergy + -ic.
synergism (n.): 1650s, "theological doctrine that human will cooperates with divine grace in regeneration" (implying that the fall did not cost the soul all inclination toward holiness), from Modern Latin synergismus, from Greek synergos "working together" (see synergy). Used in non-theological sense "a working together, cooperation" by 1910 (first of medicines).
synergist (n.): 1650s, in theology, one who holds the doctrine of synergism (q.v.); from 1876 in medicine. For ending, see -ist.
synergistic (adj.): 1818 in theology; 1876 in medicine, from synergist + -ic. General sense of "cooperative" is from 1965. Related: Synergistical (1650s); synergistically.
synergize (v.): 1881; see synergy + -ize. Related: Synergized; synergizing.
synergy (n.): 1650s, "cooperation," from Modern Latin synergia, from Greek synergia "joint work, a working together, cooperation; assistance, help," from synergos "working together," related to synergein "work together, help another in work," from syn- "together" (see syn-) + ergon "work" (see organ). Meaning "combined activities of a group" is from 1847; sense of "advanced effectiveness as a result of cooperation" is from 1957.
synod (n.): late 14c., "ecclesiastical council," from Late Latin synodus, from Greek synodos "assembly, meeting; a coming together, conjunction of planets," from syn- "together" (see syn-) + hodos "a going, a way" (see cede). Earlier in English as sinoth (early 12c.). Used by Presbyterians for "assembly of ministers and other elders" from 1593 to c. 1920, when replaced by General Council.
synodal (adj.): mid-15c., from Late Latin synodalis, from synodus (see synod).
synodic (adj.): 1630s, from Late Latin synodicus, from Greek synodikos, from synodos (see synod). Related: Synodical (1560s).
synonym (n.): "word having the same sense as another," early 15c. (but usually in plural form before 18c., or, if singular, as synonyma), from Old French synonyme (12c.) and directly from Late Latin synonymum, from Greek synonymon "word having the same sense as another," noun use of neuter of synonymos "having the same name as, synonymous," from syn- "together, same" (see syn-) + onyma, Aeolic dialectal form of onoma "name" (see name (n.)).
synonymity (n.): 1790, from synonym + -ity.
synonymous (adj.): c. 1600, of words, "denoting the same idea," from Medieval Latin synonymus, from Greek synonymos, from synonymon (see synonym). Related: Synonymously.
synonymy (n.): 1650s, "use of synonyms;" 1794, "quality of being synonymous," from French synonymie and directly from Late Latin synonymia, from Greek synonymos (see synonymous).
synopsis (n.): 1610s, "a general view, an outline," from Late Latin synopsis "a synopsis," from Greek synopsis "a general view," literally "a seeing altogether, a seeing all at once," from syn- "together" (see syn-) + opsis "sight, appearance," from PIE *okw- "to see" (see eye (n.)).