paranoid
adj.adj. feeling very worried or suspicious that other people are trying to harm you or are talking about you. You might feel this way even when there is no real reason to be afraid.
adj. characterised by an irrational or excessive suspicion of the motives of others. Often describes a state of hyper-vigilance or the belief that one is being persecuted or observed.
He felt paranoid that everyone in the office was laughing at him.
She became paranoid about her online privacy after her email account was hacked last year.
The protagonist's increasingly paranoid internal monologue creates a sense of claustrophobia, as he begins to interpret every coincidental event as a coordinated conspiracy against him.
From paranoia + -oid.
Often followed by the preposition 'about' when identifying the source of the suspicion.