A logger is a person whose job is to cut down trees, usually in a forest, and to get the wood out. It is a work word. In stories people often say lumberjack, which sounds more like a costume or a folk song; logger is still the normal name in news about forests and jobs. It is built in the simplest way: someone who works with logs — the long round pieces of a cut tree. It does not mean a person who is good at logic, and it does not mean a computer program, though that other logger exists in tech talk.