marine (n.)youdaoicibaDictYouDict[marine 词源字典]
14c., "seacoast;" see marine (adj.). Meaning "collective shipping of a country" is from 1660s. Meaning "soldier who serves on a ship" is from 1670s, a separate borrowing from French marine, from the French adjective. Phrase tell that to the marines (1806) originally was the first half of a retort expressing skepticism:
"Upon my soul, sir," answered the lieutenant, "when I thought she scorned my passion, I wept like a child."

"Belay there!" cried the captain; "you may tell that to the marines, but I'll be d----d if the sailors will believe it." ["John Moore," "The Post-Captain; or, the Wooden Walls Well Manned," 1805]
The book, a rollicking sea romance/adventure novel, was popular in its day and the remark is a recurring punch line in it (repeated at least four times). It was written by naval veteran John Davis (1774-1854) but published under the name John Moore. Walsh records that, "The marines are among the 'jolly' jack-tars a proverbially gullible lot, capable of swallowing any yarn, in size varying from a yawl-boat to a full-rigged frigate." [marine etymology, marine origin, 英语词源]
scorn (v.)youdaoicibaDictYouDict
c. 1200, from Anglo-French, Old North French escarnir (Old French escharnir), from the source of scorn (n.). Cognate with Old High German skernon, Middle Dutch schernen. Related: Scorned; scorning. Forms in Romanic languages influenced by confusion with Old French escorner "deprive of horns," hence "deprive of honor or ornament, disgrace."
specialist (n.)youdaoicibaDictYouDict
1852 (originally in the medical sense and much scorned by the GPs); see special (adj.) + -ist. Perhaps immediately from French spécialiste (1842). In general use in English by 1862. Related: Specialism.
their (pron.)youdaoicibaDictYouDict
plural possessive pronoun, c. 1200, from Old Norse þierra "of them," genitive of plural personal and demonstrative pronoun þeir "they" (see they). Replaced Old English hiera. As an adjective from late 14c. Use with singular objects, scorned by grammarians, is attested from c. 1300, and OED quotes this in Fielding, Goldsmith, Sydney Smith, and Thackeray. Theirs (c. 1300) is a double possessive. Alternative form theirn (1836) is attested in Midlands and southern dialect in U.K. and the Ozarks region of the U.S.