Final answer:
The term 'indefatigable' refers to a person or their efforts that are incapable of being tired or worn out.
Step-by-step explanation:
In English, the term "indefatigable" refers to a person or their efforts that are incapable of being tired or worn out. It is derived from the Latin word 'indefatigabilis', which means 'untiring'. An example of using this word in a sentence would be, 'Despite working long hours, she showed an indefatigable spirit and continued to pursue her goals relentlessly'.