archipelagoyoudaoicibaDictYouDict[archipelago 词源字典]
archipelago: [16] Originally, archipelago was a quite specific term – it was the name of the Aegean Sea, the sea between Greece and Turkey. Derivationally, it is a compound formed in Greek from arkhi- ‘chief’ and pélagos ‘sea’ (source of English pelagic [17] and probably related to plain, placate, and please). The term ‘chief sea’ identified the Aegean, as contrasted with all the smaller lagoons, lakes, and inlets to which the word pélagos was also applied.

An ‘Englished’ form of the word, Arch-sea, was in use in the 17th century, and in sailors’ jargon it was often abbreviated to Arches: ‘An island called Augusto near Paros, in the Arches’, Sir T Roe, Negotiations 1626. A leading characteristic of the Aegean Sea is of course that it contains a large number of islands, and from the 16th century onwards we see a strong and steady move towards what is now the word’s main meaning, ‘large group of islands’.

The immediate source of the English word was Italian arcipelago, and some etymologists have speculated that rather than coming directly from Greek arkhipélagos, this may have been a sort of folk-etymological resuscitation of it based on a misunderstanding of Greek Aigaion pelagos ‘Aegean Sea’.

=> pelagic[archipelago etymology, archipelago origin, 英语词源]
archipelago (n.)youdaoicibaDictYouDict
c. 1500, from Italian arcipelago "the Aegean Sea" (13c.), from Greek arkhipelagos, from arkhi- "chief" (see archon) + pelagos "sea" (see pelagic). The Aegean Sea being full of island chains, the meaning was extended in Italian to "any sea studded with islands." Klein, noting the absence of arkhipelagos in ancient or Medieval Greek (the modern word in Greek is borrowed from Italian) believe it is an Italian mistake for Aigaion pelagos "Aegean Sea" (Medieval Latin Egeopelagus), or influenced by that name.
lax (adj.)youdaoicibaDictYouDict
c. 1400, "loose" (in reference to bowels), from Latin laxus "wide, loose, open," figuratively "loose, free, wide," from PIE root *(s)leg- "to be slack, be languid" (cognates: Greek legein "to leave off, stop," lagos "hare," literally "with drooping ears," lagnos "lustful, lascivious," lagaros "slack, hollow, shrunken;" Latin languere "to be faint, weary," languidis "faint, weak, dull, sluggish, languid"). Of rules, discipline, etc., attested from mid-15c.
PelagianyoudaoicibaDictYouDict
1530s (n.); 1570s (adj.), from Medieval Latin Pelagianus, from Pelagius, Latinized form of the name of 4c. British monk who denied the doctrine of original sin. Combated by Augustine, condemned by Pope Zosimus in 418 C.E. His name in Welsh was said to have been Morgan, literally "sea-dweller" (hence his Church name, from Greek pelagos "sea;" see pelagic). Related: Pelagianism.
pelagic (adj.)youdaoicibaDictYouDict
"pertaining to the sea," 1650s, from Latin pelagicus, from Greek pelagikos, from pelagos "sea, high sea, open sea, main," from PIE *pelag- "to spread out" (source of Greek plagos "side," Latin plaga "hunting net, curtain, region"), possibly from root *plak- (1) "to spread out, be flat" (see placenta).
plagal (adj.)youdaoicibaDictYouDict
1590s, from Medieval Latin plagalis, from plaga "the plagal mode," probably from plagius, from Medieval Greek plagios "plagal," in classical Greek "oblique," from plagos "side" (see plagio-).
plagio-youdaoicibaDictYouDict
before vowels plagi-, word-forming element meaning "slanting, oblique," from comb. form of Greek plagios "oblique, slanting," from plagos "side," from PIE *plag- "flat, spread," from *plak- (1) "to be flat" (see placenta).
waterlogged (adj.)youdaoicibaDictYouDict
1759 (in an account of the Battle of Lagos in "Universal Magazine," September), from water (n.1) + log (n.); the notion apparently is of "reduce to a log-like condition."
WATER LOGGED, the state of a ship when, by receiving a great quantity of water into her hold, by leaking, &c., she has become heavy and inactive upon the sea, so as to yield without resistance to the efforts of every wave rushing over her decks. As, in this dangerous situation, the center of gravity is no longer fixed, but fluctuating from place to place, the stability of the ship is utterly lost. She is therefore almost totally deprived of the use of her sails, which would operate to overset her, or press the head under water. Hence there is no resource for the crew, except to free her by the pumps, or to abandon her by the boats as soon as possible. [William Falconer, "An Universal Dictionary of the Marine," London, 1784]
The verb waterlog (1779) appears to be a back-formation.
langousteyoudaoicibaDictYouDict
"A spiny lobster, especially when prepared and cooked", French, from Old Provençal lagosta, based on Latin locusta 'locust, crustacean'.