forgetyoudaoicibaDictYouDict[forget 词源字典]
forget: [OE] From a formal point of view, forget is exactly what it seems – a combination of for and get. However, this is not the modern English preposition for, but a prefix that in former times was a live building block of the language, denoting negation or exclusion. So here, forget’s Germanic ancestor *fergetan meant literally ‘not get’, hence ‘lose one’s hold on’ and metaphorically ‘lose one’s memory of’.
=> get[forget etymology, forget origin, 英语词源]
letyoudaoicibaDictYouDict
let: [OE] English has two distinct verbs let, of diametrically opposite meaning, but they are probably ultimately related. The one meaning ‘allow’ goes back to a prehistoric Germanic *lǣt- (source also of German lassen and Dutch laten) which, like the related late, is connected with a range of words denoting ‘slowness’ or ‘weariness’. It therefore appears that the underlying etymological meaning of let is ‘let go of something because one is too tired to hold on to it’.

By the time the verb reached Old English this had developed to ‘leave behind’ and ‘omit to do’, senses now defunct, as well as to ‘allow’. A close relative of the base *lǣt- was *lat-, direct ancestor of English late. From this was formed the Germanic verb *latjan, which gave English its other verb let, meaning ‘prevent’, now largely obsolete except as a noun, in the phrase without let or hindrance or as a tennis term.

=> late
abstain (v.)youdaoicibaDictYouDict
late 14c., "to withhold oneself," from Old French abstenir (14c.), earlier astenir (13c.) "hold (oneself) back, refrain, abstain (from), practice abstinence," from Latin abstinere "withhold, keep back, keep off," from ab(s)- "from, away from" (see ab-) + tenere "to hold" (see tenet). Specifically of liquor, late 14c. Of voting, 1796. Related: Abstained; abstaining.
fast (v.)youdaoicibaDictYouDict
"abstain from food," Old English fæstan "to fast" (as a religious duty), also "to make firm; establish, confirm, pledge," from Proto-Germanic *fastan "to hold fast, observe abstinence" (cognates: Old Frisian festia, Old High German fasten, German fasten, Old Norse fasta "abstain from food"), from the same root as fast (adj.).

The original meaning in prehistoric Germanic was "hold firmly," and the sense evolved via "have firm control of oneself," to "hold oneself to observance" (compare Gothic fastan "to keep, observe," also "to fast"). Perhaps the Germanic sense shifted through use of the native words to translate Medieval Latin observare in its sense "to fast." The verb in the sense "to make fast" continued in Middle English, but was superseded by fasten. Related: Fasted; fasting.
hold (v.)youdaoicibaDictYouDict
Old English haldan (Anglian), healdan (West Saxon), "to contain, grasp; retain; foster, cherish," class VII strong verb (past tense heold, past participle healden), from Proto-Germanic *haldan (cognates: Old Saxon haldan, Old Frisian halda, Old Norse halda, Dutch houden, German halten "to hold," Gothic haldan "to tend"), originally "to keep, tend, watch over" (as cattle), later "to have." Ancestral sense is preserved in behold. The original past participle holden was replaced by held beginning 16c., but survives in some legal jargon and in beholden.

Hold back is 1530s, transitive; 1570s, intransitive; hold off is early 15c., transitive; c. 1600, intransitive; hold out is 1520s as "to stretch forth," 1580s as "to resist pressure." Hold on is early 13c. as "to maintain one's course," 1830 as "to keep one's grip on something," 1846 as an order to wait or stop. To hold (one's) tongue "be silent" is from c. 1300. To hold (one's) own is from early 14c. To hold (someone's) hand "give moral support" is from 1935. Phrase hold your horses "be patient" is from 1844. To have and to hold have been paired alliteratively since at least c. 1200, originally of marriage but also of real estate.
stand-by (n.)youdaoicibaDictYouDict
also standby, 1796, "that which stands by one," originally nautical, of a vessel kept nearby for emergencies, from verbal phrase stand by "await, support, remain beside" (mid-13c.); see stand (v.) + by. Meaning "state of being ready for duty" is from 1946. In civil aviation, as an adjective meaning "without a booked ticket," from 1961. As an order to hold one's self in readiness, it is recorded from 1660s.
stand-up (adj.)youdaoicibaDictYouDict
1811, "courageous," originally of fist fights, denoting a manful contest without fake falls, from the verbal phrase (early 12c. in sense "rise to one's feet"), from stand (v.) + up (adv.). To stand up "hold oneself against an opponent" is from c. 1600; as stand up to in the same sense from 1620s. To stand up for "defend the cause of" is from c. 1600. To stand (someone) up "fail to keep an appointment" is attested from 1902. Stand-up comic first attested 1966. Catch-phrase will the real _______ please stand up? is from the popular CBS game show "To Tell the Truth," which debuted in 1956.