1. having or showing a cautious distrust of someone or something
2. causing one to have the idea or impression that something or someone is of questionable, dishonest, or dangerous character or condition

Examples

• She became suspicious when her neighbor started asking too many personal questions.
• The police found suspicious activity near the bank last night.
• His suspicious behavior made everyone uncomfortable at the meeting.
• The package looked suspicious, so we called security.
• I’m suspicious of any deal that sounds too good to be true.
• The witness gave a suspicious account of what happened.
• She cast a suspicious glance at the stranger in the hallway.