opportunity, chance, shot, break, occasion, time (in both senses: “chance for advancement, progress or profit” and “favorable circumstance or occasion”); timeliness
opponent; oppositionist; a person who will be taking the civil service entrance examination in order to get a job in the public sector, typically describing someone who's studying full-time by themselves in preparation for the exam; an applicant for a public sector job; a candidate for a public sector job