The Nasa robot that recently landed on Mars to search for signs of life is called Perseverance. It joins another rover named after a scientific virtue, Curiosity, which has been trundling around on the red planet since 2012. But why is perseverance necessarily a good thing?

The word comes, via French, from the Latin perseverare, the root of which, severus, simply means “severe”: the compound term thus means one who follows a path steadfastly without being waylaid or dismayed by difficulties. So in English since the 14th century, often with a sense of pious virtue: the angels sing in Milton’s Paradise Lost that the newly created race of humans are “happy, if they know / Their happiness, and persevere upright!”

We may assume that an extraterrestrial robot is not named for the special theological meaning (OED: “to continue until death in a state of grace”), but its handlers might hope it exemplifies another old sense – of remaining loyal, rather than going rogue in space. In the meantime you may irritate people by deliberately adopting the once-standard pronunciation “per-SEVerance”, and noting mildly that bad states of affairs can also be said to persevere, not excluding incompetent governments or plagues.

• Steven Poole’s A Word for Every Day of the Year is published by Quercus.