Noun
The act of attainting, or the state of being attainted; the extinction of the civil rights and capacities of a person, consequent upon sentence of death or outlawry; as, an act of attainder.
A stain or staining; state of being in dishonor or condemnation.
Source: Webster's dictionaryA bill of attainder is a law by which a person is immediately convicted without trial. Source: Internet
Cromwell was arraigned under a bill of attainder and executed for treason and heresy on Tower Hill on 28 July 1540. Source: Internet
However, during the reign of James I and thereafter, impeachments became more popular, as they did not require the assent of the Crown, while bills of attainder did, thus allowing Parliament to resist royal attempts to dominate Parliament. Source: Internet