suspicion
A feeling that someone or something might be doing wrong.
Suspicion is the uneasy feeling that something might be wrong or that someone might be dishonest, even without solid proof. When you have a suspicion about something, you sense that things aren't quite right, like noticing your little brother has chocolate on his face right after the cookies went missing.
Suspicion sits in that uncomfortable space between knowing and not knowing. You might be suspicious of a classmate's excuse for missing homework, or suspect that your friend is planning a surprise party because everyone keeps whispering. The word suspect can also mean the person you think might have done something wrong: police investigate suspects when solving crimes.
Having suspicions doesn't mean you're right. Sometimes suspicions turn out to be completely wrong, and you end up feeling silly for doubting someone. Other times, those gut feelings help you notice when something genuinely needs attention. A teacher might grow suspicious when two students turn in nearly identical essays, or you might become suspicious when someone's story keeps changing.
The phrase above suspicion describes someone so trustworthy that no one would ever doubt them. Being constantly under suspicion, meanwhile, means others don't fully trust you, which is an uncomfortable and unfair position if you haven't done anything wrong.