Tenure

Tenure is normally used for jobs, usually academic high-ranking jobs like professors. It is to protect professors who are teaching something that their employer, the university, might not agree with. Tenure means that these people cannot be fired without a very good reason- the job is for life. The reason for tenure is to help professors be bold about what they teach and research, so that new ideas will be developed. Or a teacher can also have a tenure. It depends how long their term has to be.
Sometimes judges also get tenure. This is so that they can make decisions based on the evidence, even if this means saying that the government, which is their employer, is wrong.