Online Etymology Dictionary

amateur: 1784, "one who has a taste for (something)," from Fr. amateur "lover of," from O.Fr., from L. amatorem (nom. amator) "lover," from amatus, pp. of amare "to love" (see Amy). Meaning "dabbler" (as opposed to professional) is from 1786.
amateurish: 1864; from amateur + -ish.
shutter: 1540s, "one who shuts" (see shut); meaning "moveable wooden or iron screen for a window" is from 1683. Photographic sense of "device for opening and closing the aperture of a lens" is from 1862. The verb is recorded from 1826. Shutter-bug "enthusiastic amateur photographer" is from 1940.
masque: "masquerade, masked ball," 1514, from M.Fr. masque (see mask). Originally the same word, it developed a special sense of "amateur theatrical performance" (1562) in Elizabethan times, when such entertainments (originally performed in masks) were popular among the nobility.
Nimrod: "great hunter," 1712, in ref. to the biblical son of Cush, referred to (Gen. x.8-9) as "a mighty hunter before the Lord." It came to mean "geek, klutz" by 1983 in teenager slang, for unknown reasons. (Amateur theories include its occasional use in "Bugs Bunny" cartoon episodes featuring rabbit-hunting Elmer Fudd as a foil; its possible ironic use, among hunters, for a clumsy member of their fraternity; or a stereotype of deer hunters by the non-hunting population in the U.S.)
aficionado: 1845, from Sp., "amateur," spec. "devotee of bullfighting," lit. "fond of," from aficion "affection," from L. affectionem (see affection).
ham (2): "overacting performer," 1882 Amer.Eng., apparently a shortening of hamfatter (1880) "actor of low grade," said to be from an old minstrel show song, "The Ham-fat Man" (1863). The song itself, a black-face number, has nothing to do with acting, so the connection must be with the quality of acting in minstrel shows, where the song was popular. The notion of "amateurish" led to the sense of "amateur radio operator" (1919). The verb in the performance sense is first recorded 1933.
dilettante: 1733, borrowing of It. dilettante "lover of music or painting," from dilettare "to delight," from L. delectare (see delight). Originally without negative connotation, "devoted amateur," the pejorative sense emerged late 18c. by contrast with professional.
sham (n.): 1677, "a trick, a hoax, a fraud," perhaps from sham, a northern dialectal variant of shame (q.v.). Sense of "Something meant to be mistaken for something else" is from 1728. The meaning in pillow-sham (1721) is from the notion of "counterfeit." The adj. is attested from 1681; the verb from 1677. Shamateur "amateur sportsman who acts like a professional" is from 1896.
profession: early 13c., "vows taken upon entering a religious order," from O.Fr. profession, from L. professionem (nom. professio) "public declaration," from professus (see profess). Meaning "occupation one professes to be skilled in" is from 1540s; meaning "body of persons engaged in some occupation" is from 1610; as a euphemism for "prostitution" (e.g. oldest profession) it is recorded from 1888. Professional (adj.) is first recorded 1747 with sense of "pertaining to a profession;" 1884 as opposite of amateur. As a noun, it is attested from 1811. Professionalism is from 1856.
gay: 1178, "full of joy or mirth," from O.Fr. gai "gay, merry" (12c.); cf. O.Sp. gayo, Port. gaio, It. gajo. Ultimate origin disputed; perhaps from Frank. *gahi (cf. O.H.G. wahi "pretty"), though not all etymologists accept this. Meaning "brilliant, showy" is from c.1300. OED gives 1951 as earliest date for slang meaning "homosexual" (adj.), but this is certainly too late; gey cat "homosexual boy" is attested in N. Erskine's 1933 dictionary of "Underworld & Prison Slang;" the term gey cat (gey is a Scot. variant of gay) was used as far back as 1893 in Amer.Eng. for "young hobo," one who is new on the road and usually in the company of an older tramp, with catamite connotations. But Josiah Flynt ["Tramping With Tramps," 1905] defines gay cat as, "An amateur tramp who works when his begging courage fails him." Gey cats also were said to be tramps who offered sexual services to women. The "Dictionary of American Slang" reports that gay (adj.) was used by homosexuals, among themselves, in this sense since at least 1920. Rawson ["Wicked Words"] notes a male prostitute using gay in reference to male homosexuals (but also to female prostitutes) in London's notorious Cleveland Street Scandal of 1889. Ayto ["20th Century Words"] calls attention to the ambiguous use of the word in the 1868 song "The Gay Young Clerk in the Dry Goods Store," by U.S. female impersonator Will S. Hays. The word gay in the 1890s had an overall tinge of promiscuity -- a gay house was a brothel. The suggestion of immorality in the word can be traced back to 1637. Gay as a noun meaning "a (usually male) homosexual" is attested from 1971.