react (v.)youdaoicibaDictYouDict[react 词源字典]
1640s, "to exert, as a thing acted upon, an opposite action upon the agent," from re- + act (v.). Chemical sense is from 1944. Related: Reacted; reacting (1610s). For sense development, see reaction. Meaning "perform again" (often re-act) is from 1650s.[react etymology, react origin, 英语词源]
reactantyoudaoicibaDictYouDict
1901 (n.), 1911 (adj.), from react + -ant.
reaction (n.)youdaoicibaDictYouDict
"action in resistance or response to another action or power," 1610s, from re- "again, anew" + action (q.v.). Modeled on French réaction, older Italian reattione, from Medieval Latin reactionem (nominative reactio), noun of action formed in Late Latin from past participle stem of Latin reagere "react," from re- "back" + agere "to do, act" (see act (v.)).

Originally scientific; physiological sense is attested from 1805; psychological sense first recorded 1887; general sense of "action or feeling in response" (to a statement, event, etc.) is recorded from 1914. Reaction time, "time elapsing between the action of an external stimulus and the giving of a signal in reply," attested by 1874.
reactionary (adj.)youdaoicibaDictYouDict
1831, on model of French réactionnaire (19c.), from réaction (see reaction). In Marxist use, "tending toward reversing existing tendencies," opposed to revolutionary and used opprobriously in reference to opponents of communism, by 1858. As a noun, "person considered reactionary," especially in politics, one who seeks to check or undo political action, by 1855.
reactivate (v.)youdaoicibaDictYouDict
1902, from re- "back, again" + activate. Related: Reactivated; reactivating; reactivation.
reactive (adj.)youdaoicibaDictYouDict
1712, from react + -ive. Related: Reactively; reactiveness; reactivity.
reactor (n.)youdaoicibaDictYouDict
"one that reacts," 1835, agent noun in Latin form from react. In nuclear sense, attested from 1945.
read (v.)youdaoicibaDictYouDict
Old English rædan (West Saxon), redan (Anglian) "to advise, counsel, persuade; discuss, deliberate; rule, guide; arrange, equip; forebode; read, explain; learn by reading; put in order" (related to ræd, red "advice"), from Proto-Germanic *redan (cognates: Old Norse raða, Old Frisian reda, Dutch raden, Old High German ratan, German raten "to advise, counsel, guess"), from PIE root *re(i)- "to reason, count" (cognates: Sanskrit radh- "to succeed, accomplish," Greek arithmos "number amount," Old Church Slavonic raditi "to take thought, attend to," Old Irish im-radim "to deliberate, consider"). Words from this root in most modern Germanic languages still mean "counsel, advise."

Sense of "make out the character of (a person)" is attested from 1610s. Connected to riddle via notion of "interpret." Transference to "understand the meaning of written symbols" is unique to Old English and (perhaps under English influence) Old Norse raða. Most languages use a word rooted in the idea of "gather up" as their word for "read" (such as French lire, from Latin legere). Read up "study" is from 1842; read out (v.) "expel by proclamation" (Society of Friends) is from 1788. read-only in computer jargon is recorded from 1961.
read (adj.)youdaoicibaDictYouDict
1580s, "having knowledge gained from reading," in well-read, etc., past participle adjective from read (v.).
read (n.)youdaoicibaDictYouDict
"an act of reading," 1825, from read (v.).
read-out (n.)youdaoicibaDictYouDict
1946, in computer sense, from read (v.) + out (adv.).
readability (n.)youdaoicibaDictYouDict
1829, from readable + -ity.
readable (adj.)youdaoicibaDictYouDict
1560s, from read (v.) + -able. Related: Readably.
reader (n.)youdaoicibaDictYouDict
Old English rædere "person who reads aloud to others; lector; scholar; diviner, interpreter," agent noun from rædan (see read (v.)). Compare Dutch rader "adviser," Old High German ratari "counselor." Old English fem. form was rædistre.
readership (n.)youdaoicibaDictYouDict
1719, "office of a reader," from reader + -ship. Meaning "total number of readers of a publication" is from 1914.
readily (adv.)youdaoicibaDictYouDict
c. 1300, from ready + -ly (2).
readiness (n.)youdaoicibaDictYouDict
mid-14c., "state of preparation, preparedness;" late 14c., "promptness;" from ready (adj.) + -ness. As "willingness" from c. 1400.
ReadingyoudaoicibaDictYouDict
county town of Berkshire, Old English Readingum (c.900), "(Settlement of) the family or followers of a man called *Read."
reading (n.)youdaoicibaDictYouDict
Old English ræding, "a reading, the act of reading" either silent or aloud, "a passage or lesson," verbal noun; see read (v.)). Meaning "interpretation" is from mid-14c. (in reference to dreams). Meaning "a form of a passage of text" is from 1550s; that of "a public event featuring reading aloud" is from 1787.
ready (adj.)youdaoicibaDictYouDict
Old English ræde, geræde "prepared, ready," of a horse, "ready for riding," from Proto-Germanic *garaidijaz "arranged" (cognates: Old Frisian rede "ready," Middle Dutch gereit, Old High German reiti, Middle High German bereite, German bereit, Old Norse greiðr "ready, plain," Gothic garaiþs "ordered, arranged"), from PIE root *reidh- "to ride" (see ride (v.)). Lengthened in Middle English by change of ending. Ready-made first attested early 15c.; ready-to-wear is from 1890.