"Insidious" is a horror movie about a family dealing with supernatural occurrences. It follows their efforts to protect their son from evil spirits who want to possess his body. The movie is known for its eerie atmosphere and suspenseful storytelling.

Insidious is used to describe something or someone who is purposeful and clever in their treachery or harmful plans. An example sentence might be: Sarah insidiously started a rumor about Jacob, knowing it would eventually be the talk of the school.

Insidious is an adjective.

Insidious

Insidious is spelled as "I-N-S-I-D-I-O-U-S".