What about pertinacious?
Is indefatigable and determined synonym?
Abu is determined to achieve a good result in the exams.
Can I replace the underlined word with indefatigable?
What about pertinacious?
I wouldn't use "pertinacious" if I were you. It's very obscure - listed in a few dictinoaries, and probably in a thesaurus (is that where you found it?), but hardly used at all.
A thesaurus lists words that are related in meaning; the closeness of the relation is variable, according to context. They are not always synonymous. "Determined' and "indefatigable", for example, can often be used in similar contexts; a person who is determined to do something may be indefatigable. But they don't have the same meaning.
Determined denotes a state of mind - determined: Definition, Synonyms and Much More from Answers.com
Indefatigable refers to tirelessness - indefatigable: Definition, Synonyms and Much More from Answers.com
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