speculation (n.)youdaoicibaDictYouDict[speculation 词源字典]
late 14c., "intelligent contemplation, consideration; act of looking," from Old French speculacion "close observation, rapt attention," and directly from Late Latin speculationem (nominative speculatio) "contemplation, observation," noun of action from Latin speculatus, past participle of speculari "observe," from specere "to look at, view" (see scope (n.1)).

Meaning "pursuit of the truth by means of thinking" is from mid-15c. Disparaging sense of "mere conjecture" is recorded from 1570s. Meaning "buying and selling in search of profit from rise and fall of market value" is recorded from 1774; short form spec is attested from 1794.[speculation etymology, speculation origin, 英语词源]
speculative (adj.)youdaoicibaDictYouDict
late 14c., "contemplative," also "purely scientific, in theory only" (opposed to practical), from Old French speculatif "worth great attention; theoretical," or directly from Late Latin speculativus, from past participle stem of speculari (see speculation). Meaning "given to (financial) speculation" is from 1763. Related: Speculatively.
speculator (n.)youdaoicibaDictYouDict
1550s, "one who engages in mental speculation," from Latin speculator "a looker-out, spy, scout, explorer; investigator, examiner," agent noun from speculari (see speculation). The financial sense is from 1778. Formerly also "observer, onlooker," especially "an occult seer" (1650s). Fem. form speculatrix attested from 1610s. Related: Speculatory.
speculum (n.)youdaoicibaDictYouDict
1590s, in surgery and medicine, "instrument for rendering a part accessible to observation," from Latin speculum "reflector, looking-glass, mirror" (also "a copy, an imitation"), from specere "to look at, view" (see scope (n.1)). As a type of telescope attachment from 1704.
spedyoudaoicibaDictYouDict
past tense and past participle of speed (v.); Old English spedde.
speech (n.)youdaoicibaDictYouDict
Old English spæc "act of speaking; power of speaking; manner of speaking; statement, discourse, narrative, formal utterance; language," variant of spræc, from Proto-Germanic *sprek-, *spek- (cognates: Danish sprog, Old Saxon spraca, Old Frisian spreke, Dutch spraak, Old High German sprahha, German Sprache "speech;" see speak (v.))

The spr- forms were extinct in English by 1200. Meaning "address delivered to an audience" first recorded 1580s.
And I honor the man who is willing to sink
Half his present repute for the freedom to think,
And, when he has thought, be his cause strong or weak,
Will risk t' other half for the freedom to speak,
Caring naught for what vengeance the mob has in store,
Let that mob be the upper ten thousand or lower.

[James Russell Lowell, "A Fable for Critics," 1848]
speechify (v.)youdaoicibaDictYouDict
"talk in a pompous, pontifical way," 1723, from speech + -ify. Related: Speechifying; speechification.
speechless (adj.)youdaoicibaDictYouDict
Old English spæcleas "permanently mute;" see speech + -less. Meaning "mute by effect of astonishment" is from late 14c. Related: Speechlessly; speechlessness.
speed (n.)youdaoicibaDictYouDict
Old English sped "success, a successful course; prosperity, riches, wealth; luck; opportunity, advancement," from Proto-Germanic *spodiz (cognates: Old Saxon spod "success," Dutch spoed "haste, speed," Old High German spuot "success," Old Saxon spodian "to cause to succeed," Middle Dutch spoeden, Old High German spuoten "to haste"), from PIE *spo-ti-, from root *spe- (1) "to thrive, prosper" (cognates: Sanskrit sphayate "increases," Latin sperare "to hope," Old Church Slavonic spechu "endeavor," Lithuanian speju "to have leisure").

Meaning "rapidity of movement, quickness, swiftness" emerged in late Old English (at first usually adverbially, in dative plural, as in spedum feran). Meaning "rate of motion or progress" (whether fast or slow) is from c. 1200. Meaning "gear of a machine" is attested from 1866. Meaning "methamphetamine, or a related drug," first attested 1967, from its effect on users.

Speed limit is from 1879 (originally of locomotives); speed-trap is from 1908. Speed bump is 1975; figurative sense is 1990s. Full speed is recorded from late 14c. Speed reading first attested 1965. Speedball "mix of cocaine and morphine or heroin" is recorded from 1909.
speed (v.)youdaoicibaDictYouDict
Old English spedan (intransitive) "to succeed, prosper, grow rich, advance," from the stem of speed (n.). Compare Old Saxon spodian, Middle Dutch spoeden "hasten," Old High German spuoton "to succeed, prosper," German sputen "make haste, hurry." Meaning "to go hastily from place to place, move rapidly" is attested from c. 1200. Transitive meaning "cause to advance toward success" is from mid-13c.; that of "send forth with quickness, give a high speed to" is first recorded 1560s; that of "to increase the work rate of" (usually with up) is from 1856. Meaning "drive an automobile too fast" is from 1908. Related: Speeded; sped; speeding.
speed-trap (n.)youdaoicibaDictYouDict
1908, from speed (n.) + trap (n.).
speeder (n.)youdaoicibaDictYouDict
"one who drives fast," 1891, agent noun from speed (v.).
speeding (n.)youdaoicibaDictYouDict
c. 1300, "success;" c. 1400 "action of aiding;" verbal noun from speed (v.). Meaning "action of driving an automobile too fast" is from 1908. Speeding ticket is from 1940.
SpeedoyoudaoicibaDictYouDict
trademark name of a brand of swimwear, 1928, originally made by McRae Hosiery Manufacturers, Australia. From speed.
speedometer (n.)youdaoicibaDictYouDict
1904, from speed + -meter. A Germanic-Greek hybrid and thus much execrated.
[T]he ancient Greeks & Romans knew what speed was, & yet no-one supposes they called it speed, whence it follows that speedo- & speedometer are barbarisms. [Fowler]
The correct classical formation is tachometer.
speedway (n.)youdaoicibaDictYouDict
1892, American English, from speed (n.) + way (n.).
speedy (adj.)youdaoicibaDictYouDict
Old English spedig "prosperous, wealthy," from speed (n.) + -y (2). Meaning "moving swiftly" is from late 14c. Related: Speedily; speediness. Speedy Gonzales, Warner Brothers studios talking cartoon mouse, debuted in a 1953 short directed by Bob McKimson.
spell (v.1)youdaoicibaDictYouDict
early 14c., "read letter by letter, write or say the letters of;" c. 1400, "form words by means of letters," apparently a French word that merged with or displaced a native Old English one; both are from the same Germanic root, but the French word had evolved a different sense. The native word is Old English spellian "to tell, speak, discourse, talk," from Proto-Germanic *spellam (cognates: Old High German spellon "to tell," Old Norse spjalla, Gothic spillon "to talk, tell"), from PIE *spel- (2) "to say aloud, recite."

But the current senses seem to come from Anglo-French espeller, Old French espelir "mean, signify, explain, interpret," also "spell out letters, pronounce, recite," from Frankish *spellon "to tell" or some other Germanic source, ultimately identical with the native word.

Related: Spelled; spelling. In early Middle English still "to speak, preach, talk, tell," hence such expressions as hear spell "hear (something) told or talked about," spell the wind "talk in vain" (both 15c.). Meaning "form words with proper letters" is from 1580s. Spell out "explain step-by-step" is first recorded 1940, American English. Shakespeare has spell (someone) backwards "reverse the character of, explain in a contrary sense, portray with determined negativity."
spell (n.1)youdaoicibaDictYouDict
Old English spell "story, saying, tale, history, narrative, fable; discourse, command," from Proto-Germanic *spellam (see spell (v.1)). Compare Old Saxon spel, Old Norse spjall, Old High German spel, Gothic spill "report, discourse, tale, fable, myth;" German Beispiel "example." From c. 1200 as "an utterance, something said, a statement, remark;" meaning "set of words with supposed magical or occult powers, incantation, charm" first recorded 1570s; hence any means or cause of enchantment.
The term 'spell' is generally used for magical procedures which cause harm, or force people to do something against their will -- unlike charms for healing, protection, etc. ["Oxford Dictionary of English Folklore"]
Also in Old English, "doctrine; a sermon; religious instruction or teaching; the gospel; a book of the Bible;" compare gospel.
spell (v.2)youdaoicibaDictYouDict
"work in place of (another)," 1590s, earlier spele, from Old English spelian "to take the place of, be substitute for, represent," related to gespelia "substitute," of uncertain origin. Perhaps related to spilian "to play" (see spiel). Related: Spelled; spelling.