Final answer:
A party-unity vote occurs when all members of a party in Congress vote together to pass a bill, indicating strong party discipline and shared policy goals.
Step-by-step explanation:
When all Republican members of Congress in the House vote to pass a bill to cut taxes, this action is often referred to as a party-unity vote. This term signifies that all or most representatives of the political party vote together in unison on a particular bill, indicating strong party discipline and shared policy goals among its members. This is in contrast to instances of gerrymandering, which refers to the act of drawing congressional districts to favor one party; a filibuster, which is a prolonged speech that obstructs progress in a legislative assembly; and pork barrel spending, which involves allocating government funds for localized projects secured solely to bring money to a representative's district.