terroryoudaoicibaDictYouDict[terror 词源字典]
terror: [14] To be terrified is etymologically to ‘shake with fear’. The ultimate ancestor of Latin terror ‘fear’ (source of English terror) and terrēre ‘frighten’ (source of English deter [16], terrible [15], terrific [17], and terrify [16]) was the Indo-European base *tre- ‘shake’, which also produced English tremble, tremor, etc. Terrorism [18] and terrorist [18] were coined in French in the 1790s to denote the activities of the Revolutionary government during the ‘Terror’, when thousands of its opponents were put to death. It broadened out towards its present-day meaning in the 19th century.
=> deter, terrible, terrify, tremble, tremor[terror etymology, terror origin, 英语词源]
terror (n.)youdaoicibaDictYouDict
early 15c., "something that intimidates, an object of fear," from Old French terreur (14c.), from Latin terrorem (nominative terror) "great fear, dread, alarm, panic; object of fear, cause of alarm; terrible news," from terrere "fill with fear, frighten," from PIE root *tres- "to tremble" (see terrible).

From c. 1500 as "fear so great as to overwhelm the mind." Meaning "quality of causing dread" is attested from 1520s. Sense of "a person fancied as a source of terror" (often with deliberate exaggeration, as of a naughty child) is recorded from 1883. Terror bombing first recorded 1941, with reference to German air attack on Rotterdam. Terror-stricken is from 1831. The Reign of Terror in French history (March 1793-July 1794) was the period when the nation was ruled by a faction whose leaders made policy of killing by execution anyone deemed an impediment to their measures; so called in English from 1801. Old English words for "terror" included broga and egesa.