selector

noun

1. 1.Someone or something which selects or chooses.
2. 2.An administrator responsible for selecting which players will play for a side.
3. 3.A matching expression in a stylesheet determining which elements in the markup are affected by a style.
4. 4.A pointer to a structure describing a segment of memory.
5. 5.A text string transmitted to a Gopher server, identifying the resource to be retrieved.