assiduous (adj.)youdaoicibaDictYouDict[assiduous 词源字典]
1530s, from Latin assiduus "attending; continually present, incessant; busy; constant," from assidere "to sit down to" (thus "be constantly occupied" at one's work); from ad "to" (see ad-) + sedere "to sit" (see sedentary). The word acquired a taint of "servility" in 18c. Related: Assiduously; assiduousness.[assiduous etymology, assiduous origin, 英语词源]
asymptote (n.)youdaoicibaDictYouDict
"straight line continually approaching but never meeting a curve," 1650s, from Greek asymptotos "not falling together," from a- "not" + syn "with" + ptotos "fallen," verbal adjective from piptein "to fall" (see symptom). Related: Asymptotic.
broken (adj.)youdaoicibaDictYouDict
late 14c., past participle adjective from break (v.). Broken record in reference to someone continually repeating the same thing is from 1944, in reference to scratches on records that cause the needle to jump back and repeat.
When Britain's Minister of State, Selwyn Lloyd[,] became bored with a speech by Russia's Andrei Vishinsky in UN debate, he borrowed a Dizzy Gillespie bebop expression and commented: "Dig that broken record." While most translators pondered the meaning, a man who takes English and puts it into Chinese gave this translation: "Recover the phonograph record which you have discarded." ["Jet," Oct. 15, 1953]
busy (adj.)youdaoicibaDictYouDict
Old English bisig "careful, anxious," later "continually employed or occupied," cognate with Old Dutch bezich, Low German besig; no known connection with any other Germanic or Indo-European language. Still pronounced as in Middle English, but for some unclear reason the spelling shifted to -u- in 15c.

The notion of "anxiousness" has drained from the word since Middle English. Often in a bad sense in early Modern English, "prying, meddlesome" (preserved in busybody). The word was a euphemism for "sexually active" in 17c. Of telephone lines, 1893. Of display work, "excessively detailed, visually cluttered," 1903.
continual (adj.)youdaoicibaDictYouDict
early 14c., continuell, from Old French continuel (12c.), from Latin continuus (see continue). That which is continual is that which is either always going on or recurs at short intervals and never comes to an end; that which is continuous is that in which there is no break between the beginning and the end. Related: Continually (c. 1300, contynuelliche).
EastlakeyoudaoicibaDictYouDict
style of furniture, 1878, often a mere debased Gothic, but at its best inspired by English designer Charles Locke Eastlake (1836-1906) and his book "Hints on Household Taste."
I find American tradesmen continually advertising what they are pleased to call 'Eastlake' furniture, with the production of which I have had nothing whatever to do, and for the taste of which I should be very sorry to be considered responsible [C.L. Eastlake, 1878]
forth (adv.)youdaoicibaDictYouDict
Old English forð "forward, onward, further; continually;" as a preposition, "during," perfective of fore, from Proto-Germanic *furtha- "forward" (cognates: Old Frisian, Old Saxon forth "forward, onward," Old Norse forð, Dutch voort, German fort), from extended form of PIE root *per- (1) "forward, through" (see per). The construction in and so forth was in Old English.
irrepressible (adj.)youdaoicibaDictYouDict
1767, from assimilated form of in- (1) "not, opposite of" + repressible (see repress).
Increase of population, which is filling the States out to their very borders, together with a new and extended network of railroads and other avenues, and an internal commerce which daily becomes more intimate, is rapidly bringing the States into a higher and more perfect social unity or consolidation. Thus, these antagonistic systems are continually coming into closer contact, and collision results.

Shall I tell you what this collision means? They who think that it is accidental, unnecessary, the work of interested or fanatical agitators, and therefor ephemeral, mistake the case altogether. It is an irrepressible conflict between opposing and enduring forces, and it means that the United States must and will, sooner or later, become either entirely a slaveholding nation, or entirely a free-labor nation. [William H. Seward, speech at Rochester, N.Y., Oct. 2, 1858]
Related: Irrepressibly.
maintain (v.)youdaoicibaDictYouDict
mid-13c., "to practice habitually," from Anglo-French meintenir (Old French maintenir, 12c.) "keep (a wife), sustain; persevere in, practice continually," from Latin manu tenere "hold in the hand," from manu, ablative of manus "hand" (see manual) + tenere "to hold" (see tenet). Meaning "to carry on, keep up" is from mid-14c.; that of "to keep oneself, to support" is from late 14c. Sense of "to defend in speech" is from mid-14c. Related: Maintained; maintaining; maintains.
saute (n.)youdaoicibaDictYouDict
1813, from French sauté, literally "jumped, bounced" (in reference to tossing continually while cooking), past participle of sauter "to jump," from Latin saltare "to hop, dance," frequentative of salire "to leap" (see salient (adj.)). As an adjective, "fried quickly," from 1869. As a verb from 1859. Related: Sauteed.
underfoot (adv.)youdaoicibaDictYouDict
c. 1200, underfot "under the feet," from under + foot (n.). Compare similarly formed Middle Dutch ondervoete. As an adjective, attested from 1590s; in reference to persons, "continually in the way," it is recorded from 1891. Middle English under fot meant "vanquished, overcome."