Sinister is a word originating from the Latin term sinister and means left, dismal, threatening, spooky, Bastard. It can also be synonymous with disaster, accident, great prejudice or wreck.
The origin of the word refers to the side left, or for an individual who is left-handed. As the vast majority of people use their right hand, when they try to carry out a task with their left hand, the result is not positive. For this reason, the word began to take on the meaning of "clumsy" or "handicapped". The meaning of the word continued to evolve, and today the word sinister has a negative connotation (in almost all cases).
O sinisterism is a synonym for mancinism or left-handedness and consists in using the left limbs to perform different tasks.
In the legal and insurance context, a claim is an accident that causes damage to some property that is insured. In this area, one of the most common accidents is accidents between motor vehicles.
In slang, and especially for younger people, the word sinister has a completely opposite meaning, describing a "nice", "cool", "awesome" person or event. Ex: