Opportunism is the conscious policy and practice of taking selfish advantage of circumstances – with little regard for principles, or with what the consequences are for others. Opportunist actions are expedient actions guided primarily by self-interested motives. The term can be applied to individual humans and living organisms, groups, organizations, styles, behaviours, and trends.
Opportunism or "opportunistic behavior" is an important concept in such fields as biology, transaction cost economics, game theory, ethics, psychology, sociology and politics.
Read more about Opportunism: Important Distinctions, Etymology, Moral Connotations of Human Opportunism, Opportunism and Human Behaviour