1. in an x-ray machine, the on–off switch controls the input of electricity to the x-ray machine.
2. the hairy part of the tail of a cow.
3. in immunology refers to the change from the production of one form or class of antibody by a B lymphocyte to another; the differentiiation occurs only in the C region of their heavy chain.
- s. sites — repetitive nucleotide sequences located between most of the C genes.
