lynch mob 
noun
A band of people intent on lynching someone.Yet those talk-show audiences can be like lynch mobs....
- They could be distinguished from more ad hoc mobs, including lynch mobs, by their structured nature and their semipermanence.
- Many episodes of anti-Mexican mob violence involve lynch mobs that broke into jails to retrieve their victims.
- underswell
- undertake
- undertaker
- undertaking
- undertenancy
- undertenant
- under the auspices of
- under the banner of
- under the baton of
- under the cosh
- under the counter (or table)
- under the gun
- under (the) hatches
- under the heel of
- under the impression that
- under the influence
- under the microscope
- under the name (of)
- under the open sky
- under the pump
- under the rose
- under the skin
- under the sod
- under the sun
- under the table