Indefatigable is positive and suggests admirable persistence and energy in continuing activities. Her indefatigable pursuit of justice impressed everyone.
Pro Tip 2/3
Intensity Emphasized
Use 'indefatigable' to express a very high level of energy or effort, more than 'hardworking'. The volunteers showed an indefatigable commitment to the cause.
Pro Tip 3/3
Academic Tone
'Indefatigable' fits well in formal or academic writing, adding sophistication to the text. His indefatigable research greatly contributed to the field.