1. A distinguishing symbol; SYN. marking, mark.
2. An implement for making a mark.
3. Some conspicuous object used to distinguish or mark something

An official who records the score during the progress of a game; SYN. scorer.

In science, a small quantity of a radioactive isotope (form of an element) used to follow the path of a chemical reaction or a physical or biological process. The location (and possibly concentration) of the tracer is usually detected by using a Geiger-Muller counter.
For example, the activity of the thyroid gland can be monitored by giving the patient an injection containing a small dose of a radioactive isotope of iodine, which is selectively absorbed from the bloodstream by the gland.
1. Any radioactive isotope introduced into the body to study metabolism or other biological processes.
2. Flight can be observed by trail of smoke; SYN. tracer bullet. + prikaži više