Dictionary:

contrarian

  (kən-trâr'ē-ən)

One who takes a contrary view or action, especially an investor who makes decisions that contradict prevailing wisdom, as in buying securities that are unpopular at the time.

An investment style that goes against prevailing market trends by buying assets that are performing poorly and then selling when they perform well.

Investopedia Says:
A contrarian investor believes that the people who say the market is going up do so only when they are fully invested and have no further purchasing power. At this point, the market is at a peak. On the other hand, when people predict a downturn, they have already sold out, at which point the market can only go up.

Contrarian investing also emphasizes out-of-favor securities with low P/E ratios.

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Investor who does the opposite of what most investors are doing at any particular time. According to contrarian opinion, if everyone is certain that something is about to happen, it won't. This is because most people who say the market is going up are fully invested and have no additional purchasing power, which means the market is at its peak. When people predict decline they have already sold out, so the market can only go up. Some mutual funds follow a contrarian investment strategy, and some investment advisers suggest only out-of-favor securities, whose price/earnings ratio is lower than the rest of the market or industry.

The noun has one meaning:

Meaning #1: an investor who deliberately decides to go against the prevailing wisdom of other investors