Suspicious (adjective)

1. Feeling or showing suspicion.
2. Having or showing a belief that something is likely to be true, without having definitive proof.
3. Having or showing a belief that someone is guilty of a crime or is doing something wrong without having definitive proof.
4. Having or showing a feeling of doubt or uncertainty about someone or something.
5. Having or showing a lack of trust or confidence in someone or something.

Origin:

From middle english suspicious, from old french suspicious, from latin suspiciousus, from suspiciō ("a looking at, a watching, a suspecting"), from suspectus, past participle of suspicere ("to look at, to watch, to suspect"), from sub- ("under") + specere ("to loo.k")

Examples:

1. The police were suspicious of the man's story.
2. He was suspicious of her motives.
3. The company was suspicious of the employee's behavior.
4. She was suspicious of the man who was following her.
5. The manager was suspicious of the employee's absence.