conjugalyoudaoicibaDictYouDict[conjugal 词源字典]
conjugal: [16] The notion underlying conjugal is of ‘joining together’. It comes from Latin conjugālis, an adjective derived from conjux ‘spouse’. This is turn was derived from conjugāre ‘join together (in marriage)’, a compound verb formed from the prefix com- ‘together’ and jugāre ‘yoke’ (a derivative of jugum ‘yoke’, which is related to English yoke and yoga). (The grammatical connotations of English conjugate [16] arise from the notion of a ‘connected’ set of verb forms.) The base of jugum, *jug-, also produced jungere ‘join’, whose derivative conjungere ‘join together’ is responsible for the parallel set of English words conjoin [14], conjunct [15], and conjunction [14].
=> conjugate, conjunction, join, yoga, yoke[conjugal etymology, conjugal origin, 英语词源]
internecineyoudaoicibaDictYouDict
internecine: [17] Etymologically, internecine denotes ‘attended by great slaughter’. Its modern connotations of ‘conflict within a group’, which can be traced back to the 18th century (Dr Johnson in his Dictionary 1755 defines it as ‘endeavouring mutual destruction’), presumably arise from the standard interpretation of inter- as ‘among, between’. But in fact in the case of internecine it was originally used simply as an intensive prefix.

The word was borrowed from Latin internecīnus, a derivative of internecāre ‘slaughter, exterminate’. This was a compound verb formed with the intensive inter- from necāre ‘kill’ (a relative of English necromancy and pernicious).
=> necromancy, pernicious
emanate (v.)youdaoicibaDictYouDict
1680s, "to flow out," from Latin emanatus, past participle of emanare "flow out," figuratively "arise from, proceed from" (see emanation). Related: Emanated; emanating.
folkways (n.)youdaoicibaDictYouDict
coined 1906 in a book of the same name by U.S. sociologist William Graham Sumner (1840-1910); see folk (n.) + way (n.).
Folkways are habits of the individual and customs of the society which arise from efforts to satisfy needs. ... Then they become regulative for succeeding generations and take on the character of a social force. [Sumner, "Folkways"]
Sumner also often is credited with ethnocentrism, which is found in the same book but is older.
pinealomayoudaoicibaDictYouDict
"A tumour of the pineal gland, thought to arise from the parenchymal cells", 1920s. From pineal + -oma.