"Peeped out" is a phrase that is often used to describe an action of looking or appearing cautiously or briefly. There are various synonyms that can be used to describe this action including glimpsed, spied, peeked, caught a sight of, caught a glimpse of, noted, detected among others. Each of these words has its own subtle difference in meaning and can be used in different contexts to convey the same idea of looking or appearing cautiously or briefly. Hence, next time you want to express the action of "peeped out", you can use any of these synonyms to add variety to your writing and express your thoughts more effectively.