to attack someone (especially verbally) unfairly in a deceitful, underhand, or treacherous manner, especially when they're not present in the place or situation that it happens. (as if stabbing them in the back). See backbite.
To make threats against (someone); to intimidate.
To endanger (someone or something); to imperil or jeopardize.
To threaten (an evil to be inflicted).
An annoying and bothersome person or thing.
The act of threatening.
A perceived threat or danger.