"bloodsucking aquatic worm," from Old English l?ce (Kentish lyce), of unknown origin (with a cognate in Middle Dutch lake). Commonly regarded as a transferred use of leech (n.2), but the Old English forms suggest a distinct word, which has been assimilated to leech (n.2) by folk etymology [see OED]. Figuratively applied to human parasites since 1784.
leech (n.2)
obsolete for "physician," from Old English l?ce, probably from Old Danish l?ke, from Proto-Germanic *lekjaz "enchanter, one who speaks magic words; healer, physician" (cognates: Old Frisian letza, Old Saxon laki, Old Norse l?knir, Old High German lahhi, Gothic lekeis "physician"), literally "one who counsels," perhaps connected with a root found in Celtic (compare Irish liaig "charmer, exorcist, physician") and Slavic (compare Serbo-Croatian lijekar, Polish lekarz), from PIE *lep-agi "conjurer," from root *leg- "to collect," with derivatives meaning "to speak" (see lecture (n.)).
For sense development, compare Old Church Slavonic baliji "doctor," originally "conjurer," related to Serbo-Croatian bajati "enchant, conjure;" Old Church Slavonic vra?i, Russian vra? "doctor," related to Serbo-Croatian vra? "sorcerer, fortune-teller." The form merged with leech (n.1) in Middle English, apparently by folk etymology. In 17c., leech usually was applied only to veterinary practitioners. The fourth finger of the hand, in Old English, was l?cfinger, translating Latin digitus medicus, Greek daktylus iatrikos, supposedly because a vein from that finger stretches straight to the heart.
例文
1. He 's fastening on that poor girl like a leech .
彼はマダラのようにあのかわいそうな娘にまとわりついている。
2. Leech and Lyons have made different classifications of meanings from different angles.
言語学者 Leech とLyonsはそれぞれ意味を分類した。
3.Jimmy Leech ，no one could run like you in school races.
ジミー？リチャ、学校の陸上競技であなたのように速く走る人はいません。
超越目標英語4冊目から
4.It 'soon proved its efficacy，and redeemed the leech 's pledge.
薬力はすぐに効果が現れ、医者の話は算数されているようだ。
5.But he hath a godly minister or two with him，and likewise a leech .