Online Etymology Dictionary

spat (n.2): "short gaiter covering the ankle" (usually only in plural, spats), 1779, shortening of spatterdash "long gaiter to keep trousers or stockings from being spattered with mud" (1680s), from spatter and dash (v.).
spat (n.3): "spawn of a shellfish," especially "spawn of an oyster," also "a young oyster," 1660s, of unknown origin, perhaps from the past tense of spit (v.1).
spate (n.): early 15c., originally Scottish and northern English, "a sudden flood, especially one caused by heavy rains or a snowmelt," of unknown origin. Perhaps from Old French espoit "flood," from Dutch spuiten "to flow, spout;" related to spout (v.). Figurative sense of "unusual quantity" is attested from 1610s.
spathic (adj.): 1788, from French spathique, from spath, from German Spath (see feldspar).
spatial (adj.): 1840 (spacial is from 1838), "occupying space," from Latin spatium + adjectival suffix -al (1); formed in English as an adjective to space (n.), to go with temporal. Meaning "of or relating to space" is from 1857. Related: Spatially.
spatter (v.): 1570s (implied in spattering), possibly a frequentative verb from the stem of Dutch or Low German spatten "to spout, burst," of imitative origin. Related: Spattered. As a noun from 1797.
spatterdash (n.): see spat (n.2).
spatula (n.): 1520s (from early 15c. as a type of medical instrument), from Latin spatula "broad piece, spatula," diminutive of spatha "broad, flat tool or weapon," from Greek spathe "broad flat blade (used by weavers)" (see spade (n.1)). Erroneous form spattular is attested from c. 1600.
spatulate (adj.): 1760, from Modern Latin spatulatus, from spatula (see spatula).
spavin (n.): disease of the hock joint of a horse, early 15c., from Middle French espavain (Modern French épavin, cognate with Italian spavenio, Spanish esparavan); in most sources said to be perhaps from Frankish *sparwan "sparrow" (see sparrow), on the supposition that a horse affected with spavin moved with a walk that reminded people of the bird's awkward gait. This seems a stretcher, and Century Dictionary admits it rests on mere resemblance of form. Related: Spavined (adj.).
spawn (v.): c. 1400, intransitive, from Anglo-French espaundre, Old French espandre "to spread out, pour out, scatter, strew, spawn (of fish)" (Modern French épandre), from Latin expandere (see expand). The notion is of a "spreading out" of fish eggs released in water. The transitive meaning "to engender, give rise to" is attested from 1590s. Related: Spawned; spawning.
spawn (n.): late 15c., "fish eggs," from spawn (v.); figurative sense of "brood, offspring," and, insultingly, of persons, is from 1580s.
spay (v.): early 15c., "stab with a sword, kill," also "remove the ovaries of (a hunting dog)," from Anglo-French espeier "cut with a sword," from Middle French espeer, from Old French espee "sword" (French épée), from Latin spatha "broad, flat weapon or tool," from Greek spathe "broad blade" (see spade (n.1)). Compare Greek spadon "eunuch." Related: Spayed; spaying.
spaz (n.): also spazz, by 1965, U.S. teen slang put-down, apparently a derogatory shortening of spastic (n.). Also used as a verb. Related: Spazzed; spazzing (often with out (adv.)).
speak (v.): Old English specan, variant of sprecan "to speak, utter words; make a speech; hold discourse (with others)" (class V strong verb; past tense spræc, past participle sprecen), from Proto-Germanic *sprek-, *spek- (source also of Old Saxon sprecan, Old Frisian spreka, Middle Dutch spreken, Old High German sprehhan, German sprechen "to speak," Old Norse spraki "rumor, report"), from PIE root *spreg- (1) "to speak," perhaps identical with PIE root *spreg- (2) "to strew," on notion of speech as a "scattering" of words.

The -r- began to drop out in Late West Saxon and was gone by mid-12c., perhaps from influence of Danish spage "crackle," also used in a slang sense of "speak" (compare crack (v.) in slang senses having to do with speech, such as wisecrack, cracker, all it's cracked up to be). Elsewhere, rare variant forms without -r- are found in Middle Dutch (speken), Old High German (spehhan), dialectal German (spächten "speak").

Not the primary word for "to speak" in Old English (the "Beowulf" author prefers maþelian, from mæþel "assembly, council," from root of metan "to meet;" compare Greek agoreuo "to speak, explain," originally "speak in the assembly," from agora "assembly").
speak (n.): c. 1300, "talk, speech," from speak (v.). Survived in Scottish English and dialect, but modern use in compounds probably is entirely traceable to Orwell (see Newspeak).
speakable (adj.): late 15c., from speak (v.) + -able. Also see unspeakable. Old English had sprecendlic "that should be spoken."
speakeasy (n.): "unlicensed saloon," 1889 (in the New York "Voice"), from verbal phrase, from speak (v.) + easy (adv.); so called from the practice of speaking quietly about such a place in public, or when inside it, so as not to alert the police and neighbors. The word gained wide currency in U.S. during Prohibition (1920-1932). In early 19c. Irish and British dialect, a speak softly shop meant "smuggler's den."
speaker (n.): c. 1300, "one who speaks," agent noun from speak (v.). Similar formation in Old Frisian spreker, Old High German sprahhari, German Sprecher. First applied to "person who presides over an assembly" c. 1400, from similar use in Anglo-French (late 14c.) in reference to the English Parliament; later extended to the U.S. House of Representatives, etc. The electric amplifier so called from 1926, short for loud-speaker.
spear (n.1): "weapon with a penetrating head and a long wooden shaft, meant to be thrust or thrown," Old English spere "spear, javelin, lance," from Proto-Germanic *speri (source also of Old Norse spjör, Old Saxon, Old Frisian sper, Dutch speer, Old High German sper, German Speer "spear"), from PIE root *sper- (1) "spear, pole" (source also of Old Norse sparri "spar, rafter," and perhaps also Latin sparus "hunting spear").
spear (n.2): "sprout of a plant," 1640s, earlier "church spire" (c. 1500); variant of spire (n.).
spear (v.): 1755, from spear (n.1). Related: Speared; spearing.
spear-head (n.): c. 1400, from spear (n.1) + head (n.). Figurative sense of "leading element" (of an attack, movement, etc.) is attested from 1893; the verb in this sense is recorded from 1938. Related: Spearheaded; spearheading.
spearmint (n.): 1530s, from spear (n.2) + mint (n.1). "Said to be a corruption of spire-mint, with reference to the pyramidal inflorescence" [Century Dictionary].
spec (n.): short for specification, 1956. Related: Specs.
special (adj.): c. 1200, "better than ordinary," from Old French special, especial "special, particular, unusual" (12c., Modern French spécial) and directly from Latin specialis "individual, particular" (source also of Spanish especial, Italian speziale), from species "appearance, kind, sort" (see species).

Meaning "marked off from others by some distinguishing quality" is recorded from c. 1300; that of "limited as to function, operation, or purpose" is from 14c. Special effects first attested 1951. Special interests in U.S. political sense is from 1910. Special pleading first recorded 1680s, a term that had a sound legal meaning once but now is used generally and imprecisely. Special education in reference to those whose learning is impeded by some mental or physical handicap is from 1972.
special (n.): "sweetheart, lover; special person or thing," c. 1300, from special (adj.) or from noun use of the adjective in Old French. Meaning "special train" is attested from 1866.
specialisation (n.): chiefly British English spelling of specialization. For spelling, see -ize.
specialist (n.): 1852 (originally in the medical sense and much scorned by the GPs); see special (adj.) + -ist. Perhaps immediately from French spécialiste (1842). In general use in English by 1862. Related: Specialism.
speciality (n.): early 15c., "a special quality or thing;" mid-15c. as "quality of being special," from Old French specialte, especialte "nature, special quality, particularity; special point, distinction," and directly from Latin specialitatem (nominative specialitas) "peculiarity, particularity" from specialis "individual, particular" (see special (adj.)). French form spécialité (especially in reference to restaurant dishes) is recorded in English from 1839.
specialization (n.): 1837, "act of becoming specialized," noun of action from specialize. Biological sense from 1862. In science and scientific education, "a direction of time and energies in one particular channel to the exclusion of others," by 1880.
specialize (v.): 1610s, "to indicate specially," from special (adj.) + -ize, perhaps on model of French spécialiser. Sense of "engage in a special study or line of business" is first attested 1881; biological sense is from 1851. Related: Specialized; specializing.
specially (adv.): late 13c., from special (adj.) + -ly (2). A doublet of especially.
specialty (n.): c. 1300, "particular affection; special attachment or favor, partiality," from Old French especialte, more vernacular form of specialite (see speciality). Compare personalty/personality; realty/reality. From early 15c. as "unusual, or extraordinary thing; specialized branch of learning; peculiar quality, distinctive characteristic."
speciation (n.): 1906; see species + -ation. The verb speciate is a back-formation attested by 1961.
specie (n.): "coin, money in the form of coins, metallic money as a medium of exchange" (as opposed to paper money or bullion), 1670s, from phrase in specie "in the real or actual form" (1550s), from Latin in specie "in kind" (in Medieval Latin, "in coin"), from ablative of species "kind, form, sort" (see species).
species (n.): late 14c. as a classification in logic, from Latin species "a particular sort, kind, or type" (opposed to genus), originally "a sight, look, view, appearance," hence also "a spectacle; mental appearance, idea, notion; a look; a pretext; a resemblance; a show or display," typically in passive senses; in Late Latin, "a special case;" related to specere "to look at, to see, behold," from PIE *spek- (see scope (n.1)). From 1550s as "appearance, outward form;" 1560s as "distinct class (of something) based on common characteristics." Biological sense is from c. 1600. Endangered species first attested 1964.
speciesism (n.): "discrimination against certain animals based on assumption of human superiority," first attested 1975 in Richard D. Ryder's "Victims of Science," from species + -ism.
specific (adj.): 1630s, "having a special quality," from French spécifique and directly from Late Latin specificus "constituting a kind or sort" (in Medieval Latin "specific, particular"), from Latin species "kind, sort" (see species). Earlier form was specifical (early 15c.). Meaning "definite, precise" first recorded 1740. Related: Specifically; specificness.
specific (n.): "a specific quality or detail," 1690s, from specific (adj.).
specification (n.): 1610s, "act of investing with some quality," from Medieval Latin specificationem (nominative specificatio), noun of action from past participle stem of Late Latin specificare "mention particularly," from Latin specificus, (see specific). With Latin -ficus, unstressed comb. form of facere "to make, do." Meaning "technical particular" is attested from 1833; short form spec first attested 1956.
specificity (n.): 1829, from French spécificité or else a native formation from specific + -ity.
specify (v.): early 14c., "to speak;" mid-14c. "to name explicitly," from Old French specifier, especefier (13c.) and directly from Late Latin specificare "mention particularly," from specificus (see specific). Related: Specified; specifying.
specimen (n.): 1610s, "pattern, model," from Latin specimen "indication, mark, example, sign, evidence; that by which a thing is known, means of knowing," from specere "to look at" (see scope (n.1)). Meaning "single thing regarded as typical of its kind" first recorded 1650s.
specious (adj.): late 14c., "pleasing to the sight, fair," from Latin speciosus "good-looking, beautiful, fair," also "showy, pretended, plausible, specious," from species "appearance, form, figure, beauty" (see species). Meaning "seemingly desirable, reasonable or probable, but not really so; superficially fair, just, or correct" in English is first recorded 1610s. Related: Speciously; speciosity; speciousness.
speck (n.): Old English specca "small spot, stain," of unknown origin; probably related to Dutch speckel "speck, speckle," Middle Dutch spekelen "to sprinkle" (compare speckle (v.)). Meaning "tiny bit" developed c. 1400. As a verb, 1570s, from the noun. Related: Specked.
speckle (v.): mid-15c. (implied in speckled), probably related to Old English specca "small spot, speck" (see speck) or from a related Middle Dutch or Middle High German word. Related: Speckled; speckling. The noun is first attested mid-15c.
specs (n.): short for spectacles, 1807.
spectacle (n.): mid-14c., "specially prepared or arranged display," from Old French spectacle "sight, spectacle, Roman games" (13c.), from Latin spectaculum "a public show, spectacle, place from which shows are seen," from spectare "to view, watch, behold," frequentative form of specere "to look at," from PIE *spek- "to observe" (see scope (n.1)).
spectacles (n.): "glass lenses to help a person's sight," early 15c., from plural of spectacle. Earlier in singular form (late 14c.).