indicator: (chemistry) a substance that changes color to indicate the presence of some ion or substance; can be used to indicate the completion of a chemical reaction or (in medicine) to test for a particular reaction
coloring material: any material used for its color
fair hearing: a hearing that is granted in extraordinary situations where the normal judicial process would be inadequate to secure due process because the person would be harmed or denied their rights before a judicial remedy became available (as in deportation or loss of welfare benefits)