'Perseverance' is literally 'being thoroughly strict with oneself' — NASA named its Mars rover for this.
Persistence in doing something despite difficulty or delay in achieving success.
From Old French perseverance, from Latin persevērantia (steadfastness, constancy, persistence), from persevērāns, present participle of persevērāre (to persist, to continue steadfastly, to abide by strictly), composed of per- (through, thoroughly, to the end) + sevērus (serious, strict, stern, grave). The PIE ancestry of sevērus is debated but may connect to *seh₁wero- (stern) or to a pre-Italic substrate. Perseverance literally means 'being thoroughly serious' — maintaining strict, unwavering commitment all the way through to completion. The word entered English
'Perseverance' literally means 'being thoroughly severe' — not harsh to others but strict with oneself, maintaining stern commitment through difficulty. NASA named its Mars rover 'Perseverance' (2020), and the word's etymology fits perfectly: the rover must be 'thoroughly serious' in its mission across an alien landscape, maintaining strict function despite extreme conditions.