lethargy

Etymology

Recorded from the late 14th century.^[1] From Middle English litargie,^[2][3] borrowed from Medieval Latin litargia,^[1][2] from Late Latin lēthargia,^[1][4] from Ancient Greek ληθαργία (lēthargía, “forgetfulness”),^[1][5] from Ancient Greek λήθαργος (lḗthargos, “forgetful”),^[5][2] from lḗthē “forgetfulness” + argós “idle”.^[4][1]

The form with -th- dates from the 1590s.^[1] Compare Lethe.^[1]

References

1. [1] [2] [3] [4] [5] [6] [7] Harper, Douglas, Online Etymology Dictionary, https://www.etymonline.com
2. [1] [2] [3] Merriam-Webster's Collegiate Dictionary, Springfield, Mass.: Merriam-Webster
3. [1] Wiktionary, the free dictionary, https://en.wiktionary.org
4. [1] [2] The American Heritage Dictionary of the English Language, Boston: Houghton Mifflin
5. [1] [2] Simpson, J. A.; Weiner, E. S. C., eds. (1989), The Oxford English Dictionary, 2nd ed., Oxford: Clarendon Press