fixed-term employee; contract worker
Refers to an employee hired for a predetermined period, as opposed to a permanent (正社員) position. Common in legal and HR contexts.
The fixed-term employee's contract expires next month.
The company introduced a system to promote fixed-term employees to permanent positions.
Compound of 有期 (fixed term) + 間 (period) + 社員 (employee). The exact historical derivation is uncertain, but it is a modern legal term.