a person who practices opportunism, or the policy of adapting actions, decisions, etc., to effectiveness regardless of the sacrifice of ethical principles: He is an extreme opportunist and always thinks the ends justify the means.
1881, from opportune + -ist. Borrowed from It. opportunismo, a word in Italian politics, later applied in French to Gambetta (1881) and then generally in English to any who seek to profit from the prevailing circumstances. Related: Opportunistic.