opportunist

noun

1. 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.

noun

1. a person who adapts his actions, responses, etc, to take advantage of opportunities, circumstances, etc

adjective

2. taking advantage of opportunities and circumstances in this way

n.1881, from opportunism (q.v.) + -ist. A word in Italian politics, later applied in French by Rochefort to Gambetta (1876) and then generally in English to any who seek to profit from the prevailing circumstances.