Indefatigable

hard

in-dih-FAT-ih-guh-bul

adjective

Definition

Persisting tirelessly; unable to be fatigued

Examples

The indefatigable researcher worked eighteen-hour days.
Her indefatigable efforts eventually led to success.

Synonyms

tirelessunwearyinginexhaustibleunflagging

Antonyms

lethargicindolentwearyexhausted

Categories

GRE Tip

Indefatigable is a hard-difficulty GRE word. On the GRE, you might see it paired with synonyms like "tireless" or "unwearying" in Sentence Equivalence questions. Look for contrast clues (however, despite, although) that signal the opposite meaning. Words like "lethargic".

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