"clayey soil used for fertilizer, mixture of clay and carbonate of lime," mid-14c. (late 13c. in place-names), from Old French marle (Modern French marne) and directly from Medieval Latin margila, diminutive of Latin marga "marl," which is said by Pliny to be a Gaulish word, but modern Celtic cognates are considered to be borrowed from English or French.
As a verb, "to manure with marl," by late 14c. (marlen, from Old French marler and Medieval Latin marlare). Medieval Latin margila also is the source of Dutch mergel, German Mergel.
"pointed iron tool used by sailors to separate strands of rope," 1620s, from spike (n.) + marlin, Middle English merlin (early 15c.) "small line of two strands, used for seizings," from Middle Dutch marlijn "small cord," from marlen "to fasten or secure (a sail)," which is probably frequentative of Middle Dutch maren "to tie, moor" (see moor (v.)). Influenced in Dutch by lijn "line" (n.).
place in Wiltshire, England, probably "Mærla's barrow," from an Old English personal name; the second element would be in reference to the ancient mound that formed the nucleus of the later castle. The famous Duke of Marlborough was John Churchill (1650–1722), soldier and statesman, leader of Allied forces during the War of the Spanish Succession, victor of Blenheim (1704).
The Marlboro brand of U.S. cigarettes were marketed from 1923, perhaps based on the earlier Philip Morris Marlborough brand in England. At first marketed as a luxury and ladies' brand, it was revived in 1950s as a men's filtered cigarette and became successful based on an advertisement campaign (from 1954) featuring a rugged cowboy, who was later known as the Marlboro Man (by 1958).
large marine game-fish, 1917, shortening of marlinspike fish (1907), from marlinspike, name of a pointed iron tool used by sailors; the fish was so called from the shape of its elongated upper jaw.