colour bar

Noun

 * 1) The segregation of people of different colour or race, especially any barrier to black people participating in activities with white people.
 * 2)  A pattern of varying tonal density that enables visual and numeric comparisons to be made across multiple printed sheets or pages.
 * 3)  A layer of good jewellery-quality opal within a rough opal.
 * 1)  A pattern of varying tonal density that enables visual and numeric comparisons to be made across multiple printed sheets or pages.
 * 2)  A layer of good jewellery-quality opal within a rough opal.
 * 1)  A layer of good jewellery-quality opal within a rough opal.