"Lynching is the practice whereby a mob, usually several dozen or several hundred persons, takes the law into its own hands in order to injure or kill a person accused of some wrong doing"(Robert L. Zangrando).
Lynching or mob violence is usually associated with racism.
Usually motivated by anger, hatred, or outrage.
"Lynching had become a ritual of interracial social control and recreation rather than simply a punishment for crime"(Robert L. Zangrando).
From TKAM: "In ones and twos, men got out of cars. Shadows became substance as lights revealed solid shapes moving toward the jail door. Atticus remained where he was. The men hid from view"(Harper Lee,202).
"This was the second time I heard Atticus ask that question in two days, and it meant somebody's man would get jumped. This was too good to miss"(Harper Lee,202).
The deal with Tom Robinson at the jail was associated with a lynch mob.
Also, these sort of mobs were common at the time in southern towns like the town of Maycomb.