The TERM 'PERIOD OF SERVICE' refers to the length of time an individual is employed in a particular job. It is usually measured in years, months, or weeks and can vary depending on the type of job and the employer's requirements. This TERM is often used to describe the length of time a person has been employed in a particular position, such as a military service member or a civil servant. It is also used to refer to the amount of time a person has been employed in a certain field, such as a doctor or lawyer.