There are several types on Investors in the market making investments in one or more categories of assets with the objective of making a profit.  To name a few Individual investors, Angel investors, Sweat equity investor, Venture capitalist funds, Investment Trusts, Mutual funds, Hedge funds and Sovereign wealth funds.. here are some of the views how investment defined by them.

Warren buffet: A good business that can be purchased for less than the discounted value of its future earnings.

George Soros: An investment that can be purchased (or sold) prior to a reflexive shift in market psychology/fundamentals that will change its perceived value substantially.

Benjamin GrahamA company that can be purchased for substantially less than its intrinsic value.

Some other examples are:

The Corporate Raider: Companies whose parts are worth more than the whole.

The Technical Analyst An investment where technical indicators have identified a change in the price trend.

The Real Estate Fixer – Upper: Run down properties that can be sold for much more than the investment required purchasing and renovating them.

The Arbitrageur: An asset that can be bought low in one market and sold simultaneously in another at a higher price.

The Crisis investor: Assets that can be bought at fire sale prices after some panic has hammered a market down.