Origin and history of vellum

early 14c., vel, "calf meat as food," from Anglo-French vel, veal, Old French veel "a calf" (12c., Modern French veau), earlier vedel, from Latin vitellus "little calf," diminutive of vitulus "calf," which is perhaps originally "yearling," if it is related, as some think, to Sanskrit vatsah "calf," literally "yearling;" Gothic wiþrus, Old English weðer (see wether; also compare veteran).

mid-13c., venim, venin, venym, "poison secreted by some animals and transferred by biting," from Anglo-French and Old French venim, venin "poison; malice," from Vulgar Latin *venimen (source also of Italian veleno, Spanish veneno) and directly from Latin venenum "poison," earlier (pre-classical) "drug, medical potion," also "charm, seduction," probably originally "love potion" (from PIE *wenes-no-, from root *wen- (1) "to desire, strive for;" source also of Venus).

Variously deformed in post-Latin languages, apparently mostly by dissimilation. The modern spelling in English from late 14c. The figurative meaning "bitter, virulent feeling or language" is attested in English from c. 1300.

a word applied at first to almost any of the larger fungi but later to the agaricoid fungi and especially the edible varieties, mid-15c., muscheron, musseroun (attested 1327 as a surname, John Mussheron), from Anglo-French musherun, Old French meisseron (11c., Modern French mousseron), perhaps from Late Latin mussirionem (nominative mussirio), though this might as well be borrowed from French.

Barnhart says "of uncertain origin." Klein calls it "a word of pre-Latin origin, used in the North of France;" OED says it usually is held to be a derivative of French mousse "moss" (from Germanic), and Weekley agrees, saying it is properly "applied to variety which grows in moss," but Klein says they have "nothing in common." For the final -m Weekley refers to grogram, vellum, venom. Modern spelling is from 1560s.

Used figuratively for something or someone that makes a sudden appearance in full form from 1590s, especially an upstart person or family, one who rises rapidly from a low station in life. In reference to the shape of clouds that rise upward and outward after explosions, etc., it is attested from 1916, though the actual phrase mushroom cloud does not appear until 1955.