lethargic

adjective

le·​thar·​gic lə-ˈthär-jik 

le-

1

: of, relating to, or characterized by laziness or lack of energy : feeling or affected by lethargy : sluggish

The patient was weak and lethargic.

2

: indifferent, apathetic

The legislature was lethargic in considering the bill.

lethargically

lə-ˈthär-ji-k(ə-)lē 

le-

adverb

Did you know?

In Greek mythology, Lethe was the name of a river in the underworld that was also called "the River of Unmindfulness" or "the River of Forgetfulness." Legend held that when someone died, they were given a drink of water from the river Lethe to forget all about their past life. Eventually this act of forgetting came to be associated with feelings of sluggishness, inactivity, or indifference. The name of the river and the word lethargic, as well as the related noun lethargy, all come from lēthē, Greek for "forgetfulness."

Synonyms of lethargic

• sleepy
• dull
• sluggish

Examples of lethargic in a Sentence

You'll need to move your lure as slowly as possible to tempt the lethargic fish into feeding … —Lenny Rudow, Boating, December 1997

… became a drifter and for a time an alcoholic and finally lapsed into lethargic self-abasement. —Stanley Karnow, New York Times Book Review, 14 Oct. 1984

The audience was cold and lethargic. It is true there were about fifty-seven applauses, but they were not roars of enthusiasm by any means. —Lady Bird Johnson 12 Jan. 1966, in A White House Diary,  1970

The patient is weak and lethargic.

a big meal always makes me feel lethargic and sleepy

Recent Examples on the Web

The 3-month-old girl spiked a fever two days earlier and had become lethargic. —Patricia Callahan, ProPublica, 19 Mar. 2026

The investigation began after a 4-month-old was taken to UPMC Washington after becoming unusually lethargic. —Shelley Bortz, CBS News, 6 Mar. 2026

Even with dramatically better affordability, rebounds from the Great Recession’s troubles were lethargic. —Jonathan Lansner, Oc Register, 2 Mar. 2026

Levy’s boyfriend claimed that a few days before that Chanco was hiding in the closet, which was one of this normal hiding spots, but appeared lethargic but seemed fine a hour later. —Staff Report, Hartford Courant, 27 Feb. 2026

Word History

Etymology

Middle English litargyk, borrowed from Anglo-French & Medieval Latin; Anglo-French litargique, borrowed from Medieval Latin litargicus, going back to Latin lēthargicus, borrowed from Greek lēthargikós, from lḗthargos "forgetful, sluggish" (of uncertain origin) + -ikos -ic entry 1

Note: The adjective lḗthargos is close phonetically to laíthargos "guileful, treacherous (of dogs that bite unexpectedly)," which invites the possibility that lḗthargos, whatever its original sense, has been recast semantically (and perhaps formally) by association with lḗthē "forgetfulness" (see lethe) and ārgós "leisured, idle." The alternation ā/ē – ai in variants is characteristic of pre-Greek substratal vocabulary in the opinion of R. Beekes (see a list of such forms in E. Furnée, Die wichtigsten konsonantischen Erscheinungen des Vorgriechischen [The Hague, 1972], pp. 336-39).

First Known Use

14th century, in the meaning defined at sense 1

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