Unobserved means not seen or noticed by anyone. When something happens unobserved, no one is watching it occur. A squirrel might bury an acorn unobserved in your backyard while everyone's inside eating dinner. A student who arrives late to class might hope to slip into their seat unobserved.

Scientists use this word frequently: they might wonder whether the moon exists in the same way when it's unobserved, or study how particles behave differently when unobserved versus when measured. In quantum physics, some things actually seem to change depending on whether they're being observed, which sounds like science fiction but appears to be true.

In everyday life, the word often appears when discussing privacy or secrecy. A spy wants to move through a building unobserved. Someone practicing a new skill might prefer to do it unobserved until they get better. The word suggests that being watched, or not being watched, matters to the situation. When you're unobserved, you're free from the awareness or judgment of others.