leech
n. countablen. a small worm that lives in water and sucks blood from animals or people. In the past, doctors used them to treat sick people, but today the word is often used for someone who takes money or help from others without giving anything back.
n. a blood-sucking annelid worm typically found in freshwater environments. Historically used for bloodletting in medicine; in modern metaphorical usage, refers to a person who parasitically exploits others.
The swimmer found a leech on his leg after leaving the pond.
He realized his cousin was a leech who only called when he needed to borrow money for rent.
While modern medicine has largely moved past bloodletting, surgeons occasionally use a medicinal leech to stimulate circulation in reattached tissue or skin grafts where blood flow is restricted.
From Middle English leche (“blood-sucking worm”), from Old English lǣċe (“blood-sucking worm”), akin to Middle Dutch lāke ("blood-sucking worm"; > modern Dutch laak).
From Middle English leche (“physician”), from Old English lǣċe (“doctor, physician”), from Proto-West Germanic lākī, from Proto-Germanic lēkijaz (“doctor”), of disputed origin, but usually thought to be connected with Proto-Celtic (compare Old Irish líaig (“charmer, exorcist, physician”)); perhaps ultimately from Proto-Indo-European *leǵ- (“to collect, gather”). Cognate with Old Frisian lētza (“physician”), Old Saxon lāki (“physician”), Old High German lāhhi (“doctor, healer”), Danish læge (“doctor, surgeon”), Gothic 𐌻𐌴𐌺𐌴𐌹𐍃 (lēkeis, “physician”). Slavic words such as Serbo-Croatian ljèkār, Polish lekarz (“physician, doctor”) are usually considered to be borrowings from Germanic.
From Middle English lechen (“to cure, heal, treat”), from Middle English leche (“doctor, physician”). Compare Swedish läka (“to heal”).
From Middle English lek, leche, lyche, from Old Norse lík (“leechline”), from Proto-West Germanic līk, from Proto-Germanic līką (compare West Frisian lyk (“band”), Dutch lijk (“boltrope”), Middle High German geleich (“joint, limb”)), from Proto-Indo-European *leyǵ- ‘to bind’ (compare Latin ligō (“tie, bind”), Ukrainian нали́гати (nalýhaty, “to bridle, fetter”), Albanian lidh (“to bind”), Hittite link- (caus. linganu-) ‘to swear’ (with -n- infix).
When used metaphorically for a person, it carries a strong negative connotation of exploitation.