Antonyms of adj indefatigable

1 sense of indefatigable

Sense 1
indefatigable, tireless, unflagging, unwearying -- (showing sustained enthusiastic action with unflagging vitality; "an indefatigable advocate of equal rights"; "a tireless worker"; "unflagging pursuit of excellence")

INDIRECT (VIA energetic) -> lethargic, unenrgetic -- (deficient in alertness or activity; "bullfrogs became lethargic with the first cold nights")

Similarity of adj indefatigable

1 sense of indefatigable

Sense 1
indefatigable, tireless, unflagging, unwearying -- (showing sustained enthusiastic action with unflagging vitality; "an indefatigable advocate of equal rights"; "a tireless worker"; "unflagging pursuit of excellence")
       => energetic (vs. lethargic) -- (possessing or exerting or displaying energy; "an energetic fund raiser for the college"; "an energetic group of hikers"; "it caused an energetic chemical reaction")