Pesky means annoyingly bothersome in a small but persistent way. A pesky mosquito buzzes around your ear at bedtime, a pesky younger sibling keeps interrupting your homework, or pesky weeds keep popping up in the garden no matter how many times you pull them out.

The word captures that particular kind of irritation that isn't serious or dangerous, just frustratingly repetitive. A pesky problem is one that won't go away easily: maybe a squeaky door hinge, a hangnail that keeps catching on things, or a math concept that trips you up again and again. Pesky things test your patience without actually causing real harm.

You might call someone a pesky pest if they're being deliberately annoying, following you around or pestering you with questions when you're trying to concentrate. Notice how pesky and pest sound similar: they both describe nuisances that are more tiresome than threatening. When your friend calls you pesky for bugging them about their weekend plans, they're saying you're being a minor nuisance, not that you're actually upsetting them.