The Oxford Thesaurus An A-Z Dictionary of Synonyms INTRO ...

lethargic adj. 1 lethargical, sluggish, slow, dull, heavy, lazy,
indolent, phlegmatic, slothful, idle, languid, languorous,
listless, fain‚ant, inactive, torpid, stuporous, comatose;
indifferent, apathetic: They were so lethargic that they did
absolutely nothing about it. 2 weary, tired, fagged out,
fatigued, enervated, weak, exhausted, drowsy, sleepy, somnolent:
I have a bad cold and feel very lethargic.
lethargy n. 1 sluggishness, sloth, dullness, heaviness, laziness,
indolence, phlegm, idleness, languidness, languor, listlessness,
dolce far niente, inactivity, inertia, torpor, stupor;
indifference, apathy: After taking the medicine, a feeling of
lethargy overtook me. 2 weariness, tiredness, fatigue,
weakness, exhaustion, drowsiness, sleepiness, somnolence: The
strident persistence of my alarm clock dragged me out of my
lethargy.
letter n. 1 character, symbol, sign: Epsilon is a letter in the Greek
alphabet. 2 missive, epistle, communication, note, line,
message, dispatch or despatch; correspondence: Write me a
letter when you get there. 3 letters. literature, the
humanities, belles-lettres, the classics; erudition, culture,
the world of letters, learning, scholarship: He is a widely
known man of letters. 4 to the letter. precisely, literally,
exactly, accurately, strictly, sic, thus, letter for letter,
literatim, word for word, verbatim: The document has been
copied to the letter.
--v. 5 inscribe, write, spell (out): She carefully lettered
the caption under the picture.
lettered adj. literate, literary, (well-)educated, erudite, scholarly,
learned, well-informed, enlightened, knowledgeable,
(well-)versed, well-read, cultured, cultivated: He was greatly
influenced by the lettered men of his time.
let-up n. cease, stop, stopping, ceasing, cessation, surcease, break,
interruption, pause, intermission, suspension, time out or off;
moderation, lessening, abatement, diminution, relief,
hesitation, respite, relaxation: I was nagged without let-up
about getting the work done by the end of the month.