Origin: Latin suffix -ous
Suspicious has 3 different meanings across 1 category:
openly distrustful and unwilling to confide
"The detective found the witness suspicious, as he refused to answer any questions about what he had seen."
not as expected
"there was something fishy about the accident"
"up to some funny business"
"some definitely queer goings-on"
"a shady deal"
"her motives were suspect"
"suspicious behavior"
Arousing suspicion.
"The man's nervous behavior and hushed whispers made him seem suspicious to everyone in the room."
The word suspicious comes from the Old French term sospecious, which was borrowed from the Latin suspiciosus. Originally meaning "looking down" or "watchful," it entered English to describe someone who is wary or distrustful of others.