What does "fool's errand" mean?

A foolish undertaking, especially one that is purposeless, fruitless, nonsensical, or certain to fail.

What is a synonym for "fool's errand"?

Common synonyms include: boondoggles.

noun

noun ·Rare ·Advanced level

Noun

1
A foolish undertaking, especially one that is purposeless, fruitless, nonsensical, or certain to fail. idiomatic
"If I were to travel only that I might be discontented with that which I can get at home, methinks I should go but on a fool's errand."
2
a fruitless mission wordnet
3
Such an undertaking, assigned as a prank. idiomatic
"Meronyms: blinker fluid, key to the midway, left-handed monkey wrench, muffler bearing, skyhook"

"If I were to travel only that I might be discontented with that which I can get at home, methinks I should go but on a fool's errand."

18th century.