Online Etymology Dictionary

sensate (adj.): c.1500, from Late Latin sensatus "gifted with sense," from sensus (see sense). As a verb from 1650s.
sensation (n.): 1610s, "a reaction to external stimulation of the sense organs," from Medieval Latin sensationem (nominative sensatio), from Late Latin sensatus "endowed with sense, sensible," from Latin sensus "feeling" (see sense (n.)). Meaning "state of shock, surprise, in a community" first recorded 1779.
The great object of life is sensation -- to feel that we exist, even though in pain. It is this 'craving void' which drives us to gaming -- to battle, to travel -- to intemperate, but keenly felt, pursuits of any description, whose principal attraction is the agitation inseparable from their accomplishment. [Lord Byron, letter, Sept. 6, 1813]
sensational (adj.): "aiming at violently excited effects," 1863, from sensation in its secondary sense. Sensationalism in literature, journalism, etc., first recorded 1865.
sensationalism (n.): 1846, in philosophy; 1865, of journalism, from sensational + -ism.
sensationalist: 1847 in philosophy; 1868 of writers; from sensational + -ist. Related: Sensationalistic.
sensationalize (v.): 1863, from sensational + -ize. Originally of audiences as well as topics.
sense (n.): c.1400, "faculty of perception," also "meaning or interpretation" (especially of Holy Scripture), from Old French sens, from Latin sensus "perception, feeling, undertaking, meaning," from sentire "perceive, feel, know," probably a figurative use of a literally meaning "to find one's way," from PIE root *sent- "to go" (cf. Old High German sinnan "to go, travel, strive after, have in mind, perceive," German Sinn "sense, mind," Old English sið "way, journey," Old Irish set, Welsh hynt "way"). Application to any one of the external or outward senses (touch, sight, hearing, etc.) first recorded 1520s.
Hornkostel cites a Negro tribe that has a separate word for seeing, but employs a common term for hearing, tasting, smelling, and touching. [A.G. Engstrom, "Philological Quarterly," XXV, 1946]
Senses "mental faculties, sanity" is attested from 1560s. Sense of humor attested by 1783.
sense (v.): "to perceive by the senses," 1590s, from sense (n.). Related: Sensed; sensing.
senseless (adj.): 1550s, "without sensation," from sense (n.) + -less. Of actions, etc., "devoid of purpose, proceeding from lack of intelligence," it is attested from 1570s. Related: Senselessly; senselessness.
sensibility (n.): late 14c., "capability of being perceived by the senses," from Latin sensibilitas, from sensibilis (see sensible). Rarely recorded until the emergence of the meaning "emotional consciousness, capacity for refined emotion" (1750s). Related: Sensibilities.
sensible (adj.): late 14c., "perceptible to the senses," from Latin sensibilis "having feeling, perceptible by the senses," from sensus, past participle of sentire "perceive, feel" (see sense (n.)). Meaning "aware, cognizant (of something)" is recorded from early 15c. Meaning "having good sense, reasonable" first recorded 1520s. Of clothes, shoes, etc., "practical rather than fashionable" it is attested from 1855.
sensibly (adv.): early 15c., "in a manner perceived to the senses," from sensible + -ly (2). Meaning "with good sense" is attested from 1755.
sensitive (adj.): c.1400, "having the function of sensation," from Middle French sensitif (13c.), from Medieval Latin sensitivus "capable of sensation," from Latin sensus, past participle of sentire "feel perceive" (see sense (n.)). Meaning "easily affected" (with reference to mental feelings) first recorded 1816; meaning "having intense physical sensation" is from 1849. Original meaning is preserved in sensitive plant (1630s). Meaning "involving national security" is recorded from 1953.
sensitivity (n.): 1803, from sensitive + -ity. Sensitivity training attested by 1954.
sensitization (n.): 1887, from sensitize + -ation.
sensitize (v.): 1856, in photography; see sensitive + -ize. Of persons from 1880. Related: Sensitized; sensitizing.
sensor (n.): 1958, from an adjective first recorded 1865, shortened from sensory (q.v.).
sensorimotor: 1855, from comb. form of sensory + motor.
sensorium (n.): from Late Latin sensorium, from sens-, past participle stem of sentire "to feel" (see sense (n.)) + -orium (see -ory).
sensory (adj.): 1749, from Latin sensorium, from sensus, past participle of sentire "to perceive, feel" (see sense (n.)).
sensual (adj.): mid-15c., "of or pertaining to the senses," from Late Latin sensualis (see sensuality). Meaning "connected with gratification of the senses," especially "lewd, unchaste" is attested from late 15c.
sensuality (n.): mid-14c., "the part of man that is concerned with the senses," from Old French sensualité, from Late Latin sensualitatem (nominative sensualitas) "capacity for sensation," from Latin sensualis "endowed with feeling, sensitive," from sensus "feeling" (see sense). Chiefly "animal instincts and appetites," hence "the lower nature regarded as a source of evil, lusts of the flesh" (1620s).
sensuous (adj.): 1640s, "pertaining to the senses" coined (from Latin sensus) by Milton to recover the original meaning of sensual and avoid the lascivious connotation that the older word had acquired by Milton's day, but by 1870 sensuous, too, had begun down the same path. Rare before Coleridge popularized it (1814).
Sensurround: 1974, proprietary name for movie special effects apparatus, coined from sense (n.) + surround.
sentence (n.): late 13c., "doctrine, authoritative teaching," from Old French sentence (12c.), from Latin sententia "thought, meaning, judgment, opinion," from sentientem, present participle of sentire "be of opinion, feel, perceive" (see sense (n.)). Loss of first -i- in Latin by dissimilation. Meaning "punishment imposed by a court" is from c.1300; that of "grammatically complete statement" is attested from mid-15c., from notion of "meaning," then "meaning expressed in words."
sentence (v.): "to pass judgment," c.1400, from sentence (n.). Related: Sentenced; sentencing. .
sententious (adj.): mid-15c., "full of meaning," from Middle French sententieux, from Latin sententiosus "full of meaning, pithy," from sententia "opinion, maxim" (see sentence). Meaning "addicted to pompous moralizing" first recorded 1590s.
sentience (n.): 1839, see sentient + -ence.
sentient (adj.): 1630s, "capable of feeling," from Latin sentientem (nominative sentiens) "feeling," present participle of sentire "to feel" (see sense (n.)). Meaning "conscious" (of something) is from 1815.
sentiment (n.): late 14c., sentement, "personal experience, one's own feeling," from Old French sentement (12c.), from Medieval Latin sentimentum "feeling, affection, opinion," from Latin sentire "to feel" (see sense (n.)).

Meaning "what one feels about something" (1630s) and modern spelling seem to be a re-introduction from French (where it was spelled sentiment by this time). A vogue word with wide application mid-18c., commonly "a thought colored by or proceeding from emotion" (1762), especially as expressed in literature or art. The 17c. sense is preserved in phrases such as my sentiments exactly.
sentimental (adj.): 1749, "pertaining to or characterized by sentiment," from sentiment + -al (1). At first without pejorative connotations; meaning "having too much sentiment" had emerged by 1793 (sentimentalist).
sentimentalism (n.): 1817, from sentimental + -ism.
sentimentalist (n.): 1783, from sentimental + -ist.
sentimentality (n.): 1770, from sentimental + -ity.
sentinel (n.): 1570s, from Middle French sentinelle, from Italian sentinella, perhaps (via a notion of "perceive, watch"), from sentire "to hear," from Latin sentire "feel, perceive by the senses" (see sense (n.)).
sentry (n.): 1610s, originally "watchtower;" perhaps a shortened variant of sentinel, which had a variant form centrinel (1590s), or worn down from sanctuary, on notion of "shelter for a watchman." Meaning "military guard posted around a camp" is first attested 1630s. Sentry-box is from 1728.
Seoul: South Korean capital, from Korean soul, literally “capital.” It was the national capital from 1392 until Japanese annexation in 1910.
sepal (n.): "leaf of the calyx," 1821, from French sépal, from Modern Latin sepalum (H.J. de Necker, 1790), coined from Latin separatus "separate" + petalum "petal."
separate (v.): late 14c., from Latin separatus, past participle of separare "to pull apart," from se- "apart" (see secret) + parare "make ready, prepare" (see pare). Sever (q.v.) is a doublet, via French. Related: Separated; separating.
separate (adj.): "detached, kept apart," c.1600, from separate (v.). Separate but equal in reference to U.S. segregation policies on railroads is attested from 1890. Separate development, official name of apartheid in South Africa, is from 1955.
separates (n.): "articles of (women's) clothing that may be worn in various combinations," 1945, from separate.
separation (n.): early 15c., from Old French separation, from Latin separationem (nominative separatio) noun of action from past participle stem of separare (see separate). Specific sense of "sundering of a married couple" is attested from c.1600. Separation of powers first recorded 1788, in "Federalist" (Hamilton), from French séparée de la puissance (Montesquieu, 1748). Separation anxiety first attested 1943.
separatism (n.): 1620s, from separate + -ism. First used in a denominational religious sense.
separatist: c.1600, from separate + -ist. First used in a denominational religious sense.
Sephardim: plural of Sephardi "a Spanish or Portuguese Jew" (1851), from Modern Hebrew Sepharaddim "Spaniards, Jews of Spain," from Sepharad, name of a country mentioned only in Obad. v:20, probably meaning "Asia Minor" or a country in it (Lydia, Phrygia), but identified by the rabbis after Jonathan Targum as "Spain."
sepia (n.): "rich brown pigment," 1821, from Italian seppia "cuttlefish" (borrowed with that meaning in English by 1560s), from Latin sepia "cuttlefish," from Greek sepia, related to sepein "to make rotten" (cf. sepsis). The color was that of brown paint or ink prepared from the fluid secretions of the cuttlefish. Meaning "a sepia drawing" is recorded from 1863.
sepoy (n.): "native of India in British military service," 1717, from Portuguese sipae, from Urdu sipahi, from Persian sipahi "soldier, horseman," from sipah "army." The Sepoy Mutiny was 1857-8.
sepsis (n.): 1876, from Modern Latin sepsis, from Greek sepsis "putrefaction," from sepein "to rot," of unknown origin.
sept (n.): 1540s, "enclosed area," from Latin septum (see septum). As "division of a nation or tribe," 1510s, "prob. a var. of sect" [OED].
September: late Old English, from Latin September, from septem "seven" (see seven). So called because it was the seventh month of the old Roman calendar, which began the year in March; Julian calendar reform (46 B.C.E.) shifted the new year back two months. For -ber suffix, see December. Replaced Old English hærfestmonað, haligmonað. Septembrist (1840) in French history refers to the massacre of the political prisoners in Paris, Sept. 2-5, 1792.