land-shark (n.)

Old English lond, land, "ground, soil," also "definite portion of the earth's surface, home region of a person or a people, territory marked by political boundaries," from Proto-Germanic *landja- (source also of Old Norse, Old Frisian Dutch, Gothic land, German Land), perhaps from PIE *lendh- (2) "land, open land, heath" (source also of Old Irish land, Middle Welsh llan "an open space," Welsh llan "enclosure, church," Breton lann "heath," source of French lande; Old Church Slavonic ledina "waste land, heath," Czech lada "fallow land"). But Boutkan finds no IE etymology and suspects a substratum word in Germanic,

Etymological evidence and Gothic use indicates the original Germanic sense was "a definite portion of the earth's surface owned by an individual or home of a nation." The meaning was early extended to "solid surface of the earth," a sense which once had belonged to the ancestor of Modern English earth (n.). Original senses of land in English now tend to go with country. To take the lay of the land is a nautical expression. In the American English exclamation land's sakes (1846) land is a euphemism for Lord.

"large, voracious fish," by 1560s, perhaps mid-15c., if an isolated instance in a diary in Middle English Compendium is the same word, of uncertain origin.

The meaning "dishonest person who preys on others," though attested from 1599 (sharker "artful swindler" in this sense is from 1594), may be the original sense, later transferred to the large, voracious marine fish. If so, it is possibly from German Schorck, a variant of Schurke "scoundrel, villain," agent noun of Middle High German schürgen (German schüren) "to poke, stir."

On an old theory, the English word is from a Mayan word, xoc, which might have meant "shark." Northern Europeans seem not to have been familiar with the larger sort of sharks before voyages to the tropics began. A slightly earlier name for it in English was tiburon, from Spanish tiburón (1520s), which probably is from a native word from South America, such as Tupi uperu "shark" (source also of Portuguese tubarão, Catalan tauró).

Middle English had hound-fish (early 14c.), which probably was used of dogfish and other small sharks. The general Germanic word seems to be represented by Old Norse har (Norwegian hai, Danis haj, Dutch haai, German Hai, also borrowed in Finnish, Latvian), which is of unknown origin. French requin is literally "grimacer," from Norman requin, from Old French reschignier "to bare the teeth, grimace."

An ancient Greek word for a shark was karkharias, from karkharos "sharp, jagged, biting," but the old theory that traces the eEnglish word to this has been dropped. Other Greek words for large selachians were aetos, bous, lamia, narkē; skylion was "dogfish." Latin used squalus, from the root of English whale (n.); Lithuanian ryklys is literally "swallower."

The English word was applied (or re-applied) to voracious or predatory persons, on the image of the fish, from 1707 (originally of pick-pockets); loan shark is attested from 1905.

There is the ordinary Brown Shark, or sea attorney, so called by sailors; a grasping, rapacious varlet, that in spite of the hard knocks received from it, often snapped viciously at our steering oar. [Herman Melville, "Mardi"]